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Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  Illinois  Urbana-Champaign 


http://archive.org/details/geologyofhardinc41well 


3 


STATE  OF  ILLINOIS 

DEPARTMENT  OF  REGISTRATION  AND  EDUCATION 

DIVISION  OF  THE 
STATE  GEOLOGICAL  SURVEY 

FRANK  W.  DE  WOLF,  Chiet 


BULLETIN  No.  41 


THE  GEOLOGY  OF  HARDIN  COUNTY 

and  the  adjoining  part  of  Pope  County 


By  Stuart  Weller 
with  the  collaboration  of  Charles  Butts.  L.  W.  Currier,  and  R.  D.  Salisbury 


In  Cooperation  with  the  United  States  Geological  Survey 


Printed  by  Authority  of  the  State  of  Illinois 


URBANA,  ILLINOIS 
1920 


STATE  OF  ILLINOIS 
DEPARTMENT  OF  REGISTRATION  AND  EDUCATION 

DIVISION  OF  THE 
STATE  GEOLOGICAL  SURVEY 

FRANK  W.  DE  WOLF,  Chief 


Committee  of  the  Board  of  Natural  Resources 
and  Conservation 

Francis  W.  Shepardson,  Chairman 

Director   of  Registration   and   Education 

Kenuric  C.  Babcock 

Representing   the   President   of   the    Uni 
versity  of  Illinois 


Rollin  D.  Salisbury 
Geologist 


Illinois  State  Journal  Co. 

Springfield,  Illinois 

State   Printers 

19  2  0 

33465 — 1M 


TABLES 

PAGK 

1.  Classification  of  rocks  in  eastern  United  States  and  southern  Illinois 80 

2.  Weller's  correlation  of  the  Lower  and  Middle  Chester  formations  of  southern  Illinois .  .  .  132 

3.  Ulrich's  correlation  of  the  Lower  and  Middle  Chester  formations  of  southern  Illinois  .  .  .  132 

4.  Production  of  domestic  fluorspar,  1913  to  1917 289 


15 


LETTER  OF  TRANSMITTAL 


State  Geological  Survey, 

Ubbana,  Apkil  1,  1920. 
Francis  W.  Shepardson,  Chairman,  and  Members  of  the  Board  of  Xatural  Resources 
and  Conservation. 

Gentlemen  :  I  submit  herewith  a  report  on  the  geology  of  Hardin  County, 
including  the  adjoining  part  of  Pope  County,  and  recommend  its  publication  as 
Bulletin  41. 

Fluorspar  mining  is  the  chief  mineral  industry  of  the  region,  and  is  of 
national  importance,  since  the  output  annually  is  more  than  two-thirds  of  the 
country's  total  production.  During  the  war  period  the  Hardin  County  mines  were 
under  guard  to  prevent  interruption  of  work;  for  the  steel  industry  depends 
on  fluorspar  as  one  of  the  important  fluxes.  Naturally,  this  report  has  special 
reference  to  the  fluorspar  deposits — their  distribution,  mode  of  occurrence,  and 
origin — and  presents  in  the  text,  and  by  display  on  the  accompanying  map,  sug- 
gestions for  prospecting  in  search  of  additional  veins  of  commercial  importance. 

The  region  deserves  study,  howrever,  for  phases  of  geology  and  geography 
ether  than  those  of  economic  importance. 

Rock  formations  of  Denovian,  Mississippian,  and  Pennsylvanian  age,  measur- 
ing between  3,500  and  4,000  feet,  are  well  exposed  along  Ohio  River  or  in  the 
dissected  upland  area  of  the  interior,  and  offer  excellent  opportunities  for  study. 
This  report  is  a  notable  contribution  to  geological  knowledge  of  the  Upper  Missis- 
sippian or  Chester  group,  serving  to  portray  with  accuracy  the  stratigraphic  suc- 
cession and  the  areal  distribution  of  formations  which  have  been  established  by 
more  than  ten  years  of  painstaking  study  extending  from  St.  Louis  to  the  south- 
eastern limits  of  Illinois. 

The  structural  geology  of  Hardin  County  is  also  of  special  interest;  the  rocks 
Lave  been  bowed  up  into  the  form  of  an  immense  dome,  then  broken  and  read- 
justed by  differential  settling  of  the  blocks,  and  intruded  by  igneous  rocks  in  the 
form  of  dikes,  sills,  and  plugs.  The  rich  ores  of  fluorspar,  lead,  and  zinc  occur 
chiefly  along  the  lines  of  old  fracture  planes. 

On  the  whole,  this  report  is  presented  wTith  assurance  that  the  subject  matter 
and  the  geologic  map  will  be  iof  great  benefit  to  the  economic  and  cultural  develop- 
ment of  the  region,  and  of  exceptional  interest  and  value  to  professional  geologists 
and  students. 

I  desire  to  acknowledge  the  public  service  rendered  by  the  several  authors, 
and    to   thank  residents   of   the   district   for   their   constant   cooperation.      Special 
credit  is  due  to  the  U.  S.  Geological  Survey  for  active  participation  in  the  topo- 
graphic and  geologic  mapping  of  the  county. 
Very  respectfully, 

Fraxk  W.  DeWolf,  Chief. 


PREFACE 

This  report  on  the  geology  of  Hardin  County,  Illinois,  is  based  upon,  field 
work  which  has  been  carried  on  by  a  number  of  persons.  The  detailed  mapping 
of  the  formations  has  been  done  by  Stuart  Weller  of  the  Illinois  State  Geological 
Survey,  and  by  Charles  Butts  and  Wallace  Lee  of  the  United  States  Geological 
Survey,  Mr.  Weller  being  responsible  for  the  area  south  of  latitude  37°  30',  and 
Mr.  Butts  and  Mr.  Lee  for  the  northern  portion  of  the  county.  Each  of  these 
workers  has  made  repeated  visits  to  the  area  mapped  by  the  other,  and  in  this 
work  full  cooperation  has  been  carried  out.  Parts  of  three  field  seasons  have  been 
devoted  to  the  work,  the  very  complex  geological  structure  of  the  area  making  it 
impracticable  to  complete  the  mapping  more  rapidly. 

In  addition  to  the  work  by  Weller,  Butts,  and  Lee,  Mr.  L.  W.  Currier  has  spent 
portions  of  two  seasons  in  the  county  in  a  study  of  the  fluorspar  deposits  which 
are  so  characteristic  of  the  area,  and  the  results  of  his  work  are  incorporated  in 
the  chapters  on  igneous  rocks  and  economic  geology.  Prof.  R.  D.  Salisbury  has 
contributed  a  chapter  on  the  geography  of  the  area. 

The  actual  writing  of  the  report,  except  the  chapters  on  igneous  rocks, 
economic  geology,  and  geography,  is  almost  entirely  the  work  of  Mr.  Weller, 
although  he  has  been  assisted  throughout  by  notes  and  suggestions  supplied  by 
Mr.  Butts.  In  apportioning  the  credit  for  the  authorship  of  this  portion  of  the 
report,  certain  chapters  or  parts  of  chapters  are  presented  under  the  name  of  one, 
and  others  under  the  names  of  both  of  these  men,  and  where  opinions  are  expressed 
and  conclusions  reached  in  chapters  or  parts  of  chapters  having  the  signature  of 
but  one  author,  that  author  alone  is  responsible  for  them. 

On  the  geological  map  that  is  presented  with  the  report,  the  area  is  extended 
for  about  five  miles  westward  into  Pope  County,  in  order  to  make  more  complete 
the  structural  area  of  which  Hardin  County  is  a  part,  and  also  to  make  available 
to  the  citizens  of  the  State  a  part  of  the  work  which  has  been  completed  in  Pope 
County,  since  the  publication  of  a  Pope  County  map  and  report  must  be  deferred 
for  several  years.  The  area  outside  of  Hardin  County  has  not  been  especially 
described  in  the  text  of  the  report,  but  the  same  formations  are  present  that  are 
exposed  in  Hardin  County,  and  the  descriptions  are  applicable  to  either  county. 

Stuart  Weller 


CONTENTS 

PAGE 

Part  I.     Introduction,  by  Stuart  Weller,  Chas.  Butts,  and  Rollin  D.  Salisbury. 17 

Chapter  I.— General  introduction,  by  Stuart  Weller  and  Chas.  Butts 19 

Location 19 

Resources 19 

Towns 20 

Topography  and  drainage 20 

Chapter  II.— Geological  introduction,  by  Stuart  Weller  and  Chas.  Butts. 23 

Sedimentary  rocks 23 

Unconformities 26 

Geologic  time 27 

Igneous  rocks 29 

Geologic  structure 29 

Dip  and  strike 31 

Topographic  development 32 

Geological  map 36 

Chapter  III. — General  geography,  by  Rollin  D.  Salisbury 39 

Relief  and  preAralent  topography 39 

The  limestone  sink  area 40 

Topography  and  roads 42 

Topography  and  farming 43 

Mantle  rock 44 

Soil 44 

Rock  cliffs 46 

History  of  the  topography. 47 

First  uplift 48 

Second  uplift 49 

Third  uplift 50 

Fourth  uplift 51 

Part  II.     Structural  geology,  by  Stuart  Weller  and  Chas.  Butts 53 

Chapter  IV. — Structural  geology 55 

Faulting 55 

Relation  of  topography  to  geologic  structure . 64 

Hicks  dome 65 

Herod  fault 66 

Lee  fault 66 

Wolrab  Mill  fault 67 

Block  between  Wolrab  Mill  and  Hogthief  Creek  faults 67 

Hogthief  Creek  fault 68 

Rock  Creek  fault 68 

Faults  a  short  distance  north  of  Hogthief  Creek  fault 69 

Peters  Creek  faults 69 

Rosiclare  fault 70 

Daisy  fault 71 

Blue  Diggings  fault 71 

7 


8  CONTENTS 

PAGE 

Big  Creek  fault 71 

Illinois  Furnace  fault 72 

Threemile  Creek  fault 73 

Wallace  Branch  fault 73 

Pell  fault 74 

Shetlerville  fault 74 

Minor  faults 74 

Part  III.     Stratigraphic  geology 77 

Chapter  V. — Pre-Devonian,  by  Stuart  Weller  and  Chas.  Butts. 79 

Chapter  VI. — Devonian,  by  Chas.  Butts  and  Stuart  Weller 83 

General  statement 83 

Limestone  of  Devonian  age 84 

Areal  distribution 84 

Lithologic  character 84 

Stratigraphic  relations 85 

Thickness 85 

Paleontology 85 

Chattanooga  shale 87 

Name  and  distribution 87 

Lithologic  character 88 

Thickness 88 

Paleontology. 89 

Correlation 89 

Stratigraphic  relations ( 89 

Chapter  VII. — Lower  Mississippian,  by  Chas.  Butts  and  Stuart  Weller 91 

General  statement 91 

Osage  formation 92 

Name  and  distribution 92 

Lithologic  character 93 

Thickness 94 

Paleontology ' 94 

Correlation 95 

Meramec  group,  by  Stuart  Weller 96 

Warsaw  limestone 97 

Name  and  distribution 97 

Lithologic  character 98 

Thickness 99 

Paleontology 99 

Correlation 100 

St.  Louis  limestone,  by  Stuart  Weeler 100 

Name  and  distribution 100 

Lithologic  character 102 

Stratigraphic  relations 104 

Thickness 104 

Paleontology 104 

Ste.  Genevieve  limestone,  by  Stuart  Weller 106 

Name  and  distribution 106 

Subdivisions  of  the  Ste.  Genevieve  limestone 109 

Lithologic  character  of  the  Fredonia  limestone  member 110 

Lithologic  character  of  the  Rosiclare  sandstone  member Ill 

Lithologic  character  of  the  'Lower  Ohara"  limestone  member. 112 


CONTENTS  9 

PAGE 

Detailed  sections 112 

Thickness 113 

Stratigraphic  relations 114 

Paleontology 115 

Chapter  VIII. — Upper  Mississippian  series,  Chester  group,  by  Stuart  Weller 121 

General  statement 121 

Historical  review 121 

Shetlerville  formation 133 

Name  and  distribution 133 

Lithologic  character 134 

Thickness 134 

Stratigraphic  relations 135 

Paleontology 136 

Correlation 142 

Renault  formation 142 

Name  and  distribution 142 

Lithologic  character 144 

Thickness 145 

Stratigraphic  relations 145 

Paleontology 147 

Correlation 150 

Bethel  sandstone 159 

Name  and  distribution 159 

Lithologic  character 161 

Detailed  sections 162 

Stratigraphic  relations 163 

Thickness 163 

Paleontology 164 

Correlation 164 

Paint  Creek  formation 164 

Name  and  distribution 164 

Lithologic  character 167 

Detailed  sections .  .  . 168 

Thickness 169 

Stratigraphic  relations 169 

Paleontology 170 

Correlation 171 

Cypress  sandstone 175 

Name  and  distribution 175 

Lithologic  character 176 

Thickness 176 

Stratigraphic  relations .  177 

Paleontology 177 

Correlation 178 

Golconda  formation 178 

Name  and  distribution 178 

Lithologic  character 180 

Thickness 181 

Stratigraphic  relations 181 

Paleontology .* 182 

Correlation 186 


10  CONTENTS 

PAGE 

Hardinsburg  sandstone 187 

Name  and  distribution 187 

Lithologic  character 189 

Thickness 189 

Stratigraphic  relations 190 

Paleontology 190 

Correlation 190 

Glen  Dean  limestone 191 

Name  and  distribution 191 

Lithologic  character 193 

Thickness 194 

Stratigraphic  relations 195 

Paleontology 195 

Correlation 197 

Tar  Springs  sandstone 198 

Name  and  distribution 198 

Lithologic  character 199 

Thickness 200 

Stratigraphic  relations 200 

Paleontology 201 

Correlation 201 

Vienna  limestone  and  Waltersburg  sandstone 202 

Menard  limestone 202 

Name  and  distribution 202 

Lithologic  character 204 

Thickness 206 

Stratigraphic  relations 206 

Paleontology 207 

Correlation 209 

Palestine  sandstone 209 

Name  and  distribution 209 

Lithologic  character 211 

Thickness 211 

Stratigraphic  relations 211 

Paleontology 212 

Correlation 212 

Clore  formation 212 

Name  and  distribution 212 

Lithologic  character 213 

Thickness 214 

Stratigraphic  relations 214 

Paleontology 214 

Correlation 215 

Degonia  sandstone 216 

Name  and  distribution 216 

Lithologic  character 217 

Thickness 217 

Stratigraphic  relations 217 

Paleontology 217 

Correlation 218 


CONTENTS  11 


PAGE 

Kinkaid  limestone 218 

Name  and  distribution 218 

Lithologic  character 219 

Thickness 220 

Stratigraphic  relations 220 

Paleontology 221 

Correlation 222 

Chapter  IX. — Pennsylvanian,  by  Chas.  Butts 223 

Sub-Pennsylvanian  unconformity. 223 

Pottsville  group 225 

Casey ville  formation 225 

Name  and  distribution 225 

Lithologic  character 225 

Battery  Rock  coal 226 

Thickness 227 

Paleontology 227 

Correlation 227 

Tradewater  formation 228 

Name  and  distribution 228 

Lithologic  character 228 

Coal  beds 228 

Thickness 229 

Paleontology  and  correlation 229 

Chapter  X.— Surficial  deposits,  by  Stuart  Weller 231 

General  statement 231 

Residual  deposits 231 

Alluvial  deposits 232 

Wind  blown  deposits 233 

Part  IV.     Igneous  rocks,  by  L.  W.  Currier 235 

Chapter  XI. — Igneous  rocks 237 

Part  V.     Economic  geology,  by  L.  W.  Currier  and  Chas.  Butts 245 

Chapter  XII. — Economic  geology 247 

Mineral  resources 247 

Fluorspar,  lead,  and  zinc,  by  L.  W.  Currier. 247 

General  statement 247 

Brief  history  of  mining  development 247 

The  occurrence  of  fluorspar 248 

Vein  deposits 248 

Minerals  of  the  veins . 252 

Bedding  deposits 254 

Superficial  deposits 256 

Paragenesis  of  minerals 257 

Metasomatic  relations  of  minerals 259 

Description  of  photomicrographs  and  figures  illustrating    paragehsis 260 

Origin  of  the  deposits 275 

Views  of  previous  writers 275 

Summary  of  genetic  evidence 278 

Chemical  considerations 279 

Geologic  history  of  the  deposits 281 


12  CONTENTS 

PAGE 

Mining  and  milling  methods 282 

Mining  methods 282 

Milling  methods 283 

Economic  considerations 287 

Production 289 

Suggestions  for  prospecting 290 

Principal  mines  of  Hardin  County 293 

Iron  ore,  limestone,  road  metal,  oil  and  gas,  by  Chas.  Butts 304 

Iron  ore 304 

Limestone 305 

Road  metal 306 

Oil  and  gas  possibilities 307 

Structure 307 

Possible  oil-bearing  strata 309 

Part  VI.     Paleontology,  by  Stuart  Weller 311 

Chapter  XIII.— Paleontology 313 

Lower  Chester  and  related  species 314 

Golconda  and  Lower  Okaw  species 355 

Miscellaneous  Chester  species 368 

Plates  and  explanations 379 

Index 402 


ILLUSTRATIONS 


Plate  page 

I.     Geologic  map  of  Hardin  County  and  the  adjoining  part  of  Pope  County In  pocket 

II — A  to  G.     Photomicrographs  of  vein  material  from  the  Rosiclare  and  Fairview  mines. .  .261 
III.     Map  showing  geologic  structure  in  parts  of  Hardin,  Pope,  and  Saline  counties  .  .In  pocket 

IV-XI.     Fossils  from  the  rock  strata  of  Hardin  County 383 

Figure 

1.  Diagram  to  show  the  movement  of  rock  strata  in  reverse  and  in  normal  faulting.  ...   31 

2.  Diagram  to  show  the  application  of  the  terms  diy  and  strike 32 

3.  Map  showing  the  faults  and  the  structural  segments  of  Hardin  County  and  the 

adjoining  part  of  Pope  County 61 

4.  Bluff  of  St.  Louis  limestone  at  Tower  Rock 101 

5.  Bluff  of  St.  Louis  limestone  two  miles  west  of  Cave  in  Rock 103 

6.  St.  Louis  limestone  with  Lithostronon,  on  the  Ohio  River  bank  west  of  Cave  in  Rock .  .  105 

7.  Basal  Ste.  Genevieve  (Fredonia)  limestone  at  Elizabethtown Ill 

8.  Cherty  Ste.  Genevieve  limestone  half  a  mile  east  of  Elizabethtown. 112 

9.  Unconformity  between  the   "Lower   Ohara"   and  the   Shetlerville  formations  in 

Fairview  bluff  below  Rosiclare 135 

10.  Possible  unconformity  between  the  Shetlerville  and  Renault  formations  in  Fairview 

bluff  below  Rosiclare 136 

11.  Unconformable  contact  of  Bethel  sandstone  on  the  Renault  limestone  east  of  Cave 

in  Rock 146 

12.  Unconformable  contact  of  Bethel  sandstone  on  the  Renault  limestone,  east  of  Cave 

in  Rock 147 

13.  Diagram  showing  the  relations  of  the  Mississippian  and  Pennsylvanian  systems  in 

Hardin  County  and  in  the  Appalachian  coal  field .  .  .224 

14.  Dike  cutting  Ste.  Genevieve  limestone  at  Orrs  Landing  2  miles  southwest  of  Eliza- 

bethtown   238 

15.  Renault  limestone  injected  by  a  sill  at  Downeys  bluff  south  of  Rosiclare 239 

16.  Panoramic  view  of  the  site  of  the  "volcanic  plug"  south  of  Sparks  Hill 242 

17.  Exposure  of  volcanic  rock  near  Sparks  Hill 243 

18.  View  of  a  mass  of  the  volcanic  rock  exposed  in  fig.  16 243 

19.  Sketch  map  of  the  Illinois  fluorspar  district    showing  locations  of  principal  mines 

and  prospects,  igneous  rocks,  and  mineralized  faults  and  veins- 249 

20.  Diagram  illustrating  the  effects  of  displacement  on  the  shape  of  a  fault  fissure  when 

the  fault  is  undulatory 251 

21.  Map  showing  distribution  of  principal  open-cuts  of  the  Pierce  mines  and  the  apparent 

direction  of  the  veins 257 

22.  Idealized  section  of  a  fluorspar  vein 258 

23.  Mill  and  Good  Hope  shaft  of  the  Fairview  Fluorspar  and  Lead  Company 283 

24.  Mill  and  Rosiclare  mine  of  the  Rosiclare  Lead  and  Fluorspar  Company 284 

25.  Diagram  showing  the  development  of  the  fluorspar  industry  in  the  United  States, 

1909-1916,  and  the  contributions  made  by  Illinois 291 

26.  Idealized  geologic  section  through  the  air  shaft  of  the  Rosiclare  mine 294 

13 


14  ILLUSTRATIONS 

Figure  page 

27.  Idealized  geologic  section  through  the  new  Good  Hope  shaft 296 

28.  Idealized  geologic  section  through  the  Annex  shaft 297 

29.  Map  and  idealized  geologic  section  to  show  the  vein  relationships  and  stratigraphy 

at  the  Blue  Diggings  shaft 299 

30.  View  of  a  mass  of  fluorspar  on  the  weathered  apex  of  a  vein 303 


PART   I 

INTRODUCTION 

By  Stuart  Weller,  Chas.  Butts,  and  Rollin  D.  Salisbury 


-2  G 


CHAPTER  I— GENERAL  INTRODUCTION 

By   Stuart  Weller  and   Chas.   Butts 


Location 


Near  the  southern  extremity  of  the  State  of  Illinois,  extending  from 
Mississippi  River  on  the  west  to  Ohio  River  on  the  east,  there  is  a  belt  of 
high,  rough  land  that  is  commonly  referred  to  as  a  spur  of  the  Ozarks.  This 
rugged  area  extends  eastward  from  northern  Union  County,  across  Johnson, 
Pope,  and  Hardin  counties,  and  spreads  northward  into  the  southern  portion 
of  Jackson^  Williamson,  Saline,  and  Gallatin  counties.  The  highest  point,  so 
far  as  known,  is  on  Williams  Hill  in  northeastern  Pope  County,  which  rises 
to  an  elevation  of  1065  feet  above  sea  level,  but  a  number  of  points  lie  between 
900  and  1000  feet.  To  the  north  of  the  Ozark  country,  the  general  surface 
level  is  near  400  feet  above  sea  level,  and  south  of  it  the  Ohio  River  flood 
plain  is  near  300  feet.     The  width  of  the  strip  is  approximately  25  miles. 

Hardin  County  is  in  the  extreme  southeastern  portion  of  the  State  and 
lies  wholly  within  the  Ozark  country.  Its  northern  boundary,  separating  it 
from  Gallatin  and  Saline  counties,  lies  almost  exactly  along  the  crest  of  the 
ridge.  Its  surface  slopes  southward  to  Ohio  River,  which  bounds  the  county 
along  both  its  eastern  and  southern  borders.     To  the  west  lies  Pope  County. 

Resources 

Although  Hardin  County,  as  one  of  the  most  important  producing  areas 
of  fluorspar  in  the  world,  has  long  been  known  for  its  mineral  products,  the 
rugged  character  of  its  surface  long  discouraged  the  building  of  railways,  and 
indeed,  until  recently  it  was  one  of  the  two  counties  in  Illinois  with  no  rail- 
road transportation,1  and  without  Ohio  River  the  mineral  products  of  the 
county  could  never  have  been  marketed.  The  lack  of  adequate  transportation 
facilities  has  kept  the  mineral  production  essentially  localized  to  mines  near 
the  river,  and  numerous  promising  pro  pects  have  never  been  fully  developed 
because  of  the  lack  of  means  for  bringing  the  product  of  the  mines  to  market. 

The  chief  industry  of  the  county,  and  practically  the  only  one  aside  from 
mining,  is  agriculture,  and  this  must  always  remain  the  source  of  livelihood 
of  the  greater  number  of  residents.  Because  of  its  rugged  character  much  of 
the  land  is  not  tillable,  and  manv  acres  which  are  now  cultivated  or  which 


1  The  I.   C.   Railroad  has  extender!  its  Golconda  branch  eastward  into  Harden   County, 
and  trains  are  now  running  to  Rosiclare. 

19 


20  GEOLOGY    OF    HARDIN    COUNTY 

have  been  tilled  hi  the  past,  should  never  have  been  plowed.  The  upland 
soil,  which  was  originally  the  soil  of  nearly  the  whole  county,  is  loess,  a  wind 
blown  deposit  which  covered  all  the  hills.  This  loess  soil  is  exceedingly  liable 
to  be  washed  and  gullied,  and  when  a  hill  slope  once  starts  to  wash  it  is 
utterly  destroyed  for  agricultural  purposes  in  a  comparatively  few  years. 
Such  surfaces  should  be  kept  in  timber,  or  they  should  be  covered  with  forage 
grasses  which  would  prevent  the  destruction  of  the  soil  and  would  at  the  same 
time  furnish  excellent  pasture  land. 

Towns 

The  three  most  important  towns  of  the  county  are  Elizabethtown,  Eosi- 
clare,  and  Cave  in  Eock,  all  of  them  situated  upon  the  bank  of  Ohio  Eiver, 
and  all  have  been  entirely  dependent  upon  river  transportation  for  their  con- 
nection with  the  outer  world  until  the  recent  extension  of  the  railroad  to 
Eosiclare.  Elizabethtown,  with  633  inhabitants1,  is  the  county  seat,  and 
is  located  some  distance  west  of  the  middle  of  the  southern  boundary  of 
the  county.  The  next  most  important  town  is  Eosiclare  with  609  inhabitants1, 
situated  about  three  miles  below  Elizabethtown.  It  is  the  center  of  the 
fluorspar  mining  industry  of  the  county,  and  is  supported  by  the  Eosiclare 
and  Fairview  mines,  located  in  its  outskirts.  These  are  the  only  two  mines 
in  the  county  which  have  been  fully  developed  by  modern  mining  engineering 
methods.  Cave  in  Eock,  a  town  smaller  than  either  Elizabethtown  or  Eosi- 
clare, is  situated  about  eight  miles  east  of  the  county  seat.  Other  smaller 
communities,  consisting  of  only  a  store  or  two  and  a  few  residences,  are 
Karbers  Eidge,  Hicks,  Eichorn,  and  Shetlerville,  all  of  them  towards  the 
western  portion  of  the  county.  Elsewhere  throughout  the  county  there  are  a 
number  of  country  stores,  near  some  of  which  there  are  one  or  two  residences. 
The  total  population  of  the  county,  as  shown  by  the  1910  census,  is  7015. 

Topography  and  Drainage 

Hardin  County  has  reached  the  mature  stage  of  topographic  develop- 
ment. There  is  but  little  level  land,  the  whole  surface  is  well  drained,  and 
the  relief  is  great.  The  highest  point  in  the  county  is  at  High  Knob,  the 
southern  spur  of  which  lies  nearly  on  the  line  between  Hardin  and  Gallatin 
counties,  north  of  Karbers  Eidge.  This  point  rises  to  an  elevation  of  900  feet 
above  sea  level.  Another  hill  two  and  one-half  miles  west  of  High  Knob,  and 
lying  just  within  the  northern  boundary  of  the  county,  rises  to  an  elevation 
of  a  little  over  860  feet.  Both  of  the  high  points  mentioned  are  included  in 
a  series  of  high  hills  which  mark  the  crest  of  the  Ozark  belt  across  southern 
Illinois.  The  northern  boundary  of  the  county  lies  almost  along  this  crest  of 
the  high  land,  and  the  general  surface  slopes  southward  to  Ohio  Eiver,  the 

1  Census  of  1910. 


GENERAL    INTRODUCTION  21 

elevation  of  whose  bank  is  between  300  and  320  feet.     The  total  relief  of  the 
county  is,  therefore,  almost  600  feet. 

The  southward  sloping  surface  of  the  county  is  deeply  dissected  by  the 
streams  which  drain  it.  The  longest  stream  that  is  entirely  included  within 
the  county  is  Big  Creek,  which  rises  within  a  quaiter  of  a  mile  of  the  northern 
boundaiy  of  the  county,  about  two  miles  northeast  of  Karbers  Eidge.  The 
elevation  of  the  head  of  the  stream  is  020  feet,  but  one  tributary  very  close 
to  the  head  rises  at  an  elevation  of  760  feet.  The  approximate  length  of  this 
stream  is  16  miles,  and  in  that  distance  it  falls  not  less  than  450  feet.  All 
but  100  feet  of  this  fall  is  in  the  upper  five  miles  of  the  stream's  course,  and 
250  feet  of  fall  takes  place  in  the  first  mile.  The  other  streams  in  the  county 
resemble  Big  Creek  in  their  profiles,  the  fall  being  rapid  in  the  upper  parts  of 
their  courses,  and  becoming  much  more  gentle  below.  Along  the  lower 
stretches  of  the  larger  streams,  where  they  have  a  gentle  gradient,  narrow 
alluvial  bottoms  have  been  developed,  but  they  are  not  continuous  along  the 
stream  valleys  and  nowhere  are  they  very  wide.  The  Ohio  River  bottoms  are 
nowhere  extensively  developed  within  the  county,  the  rocky  bluffs  rising  from 
the  river  banks  along  most  of  the  eastern  and  southern  borders.  A  strip  of 
bottom  land  is  present  in  the  southeastern  part  of  the  county,  from  Gentry 
Landing  extending  a  little  over  five  miles  to  a  point  about  two  miles  east  of 
Cave  in  Rock.  Another  stretch  of  bottom  land  in  the  southwestern  part  of 
the  county  extends  from  Fairview  to  Shetlerville,  about  three  miles.  In 
neither  of  these  areas  do  the  bottoms  attain  a  maximum  width  of  over  one 
mile. 

Two  distinct  types  of  drainage  are  exhibited  in  Hardin  County.  The 
greater  portion  of  the  county  is  drained  by  ordinary  surface  streams,  but  in 
a  considerable  area  northwest  of  Cave  in  Rock,  and  in  a  small  area  in  the 
southwestern  part  of  the  county,  the  drainage  is  underground,  through  sink- 
holes. 

The  entire  county  drains  into  Ohio  River,  although  much  of  it  does  not 
drain  directly  into  that  stream.  The  larger  basins  that  are  wholly  within 
the  county  and  that  are  directly  tributary  to  the  Ohio,  in  the  order  of  their 
magnitude,  are,  Big  Creek,  Honey  Creek,  Threemile  Creek,  Peters  Creek, 
Hosick  Creek,  and  Wallace  Branch  basins.  Other  areas  drained  by  shorter 
streams  that  are  directly  tributary  to  the  Ohio  lie  in  the  eastern  part  of  the 
county  between  Honey  Creek  and  the  mouth  of  Saline  River,  another  along 
the  southern  border  of  the  county  between  Honey  Creek  and  Peters  Creek, 
and  still  another  about  Rosiclare.  In  the  northeastern  portion  of  the  countv 
there  is  a  considerable  area,  drained  largely  by  Goose  Creek  and  Rock  Creek, 
which  is  tributary  to  Saline  River,  and  in  the  western  part,  especially  the 
northwestern  part  of  the  county,  a  rather  large  area  drains  westward  into 
Grand  Pierre  Creek  situated  in  Pope  County,  and  then  into  the  Ohio. 


22  GEOLOGY    OF   HARDIN    COUNTY 

The  larger  of  the  two  areas  that  have  no  surface  outlet  for  their  waters 
lies  northwest  of  Cave  in  Hock;  it  is  dotted  with  sink-holes  which  must  con- 
nect with  underground  stream  channels  which  find  their  outlets  through  the 
numerous  springs  present  in  the  county.  The  central  portion  of  this  large 
sink  area  lies  near  the  common  corner  of  sees.  2  and  3,  T.  12  S.,  R.  9  E.,  and 
sees.  34  and  35,  T.  11  S.,  E.  9  E.  The  other  and  much  smaller  area  with 
underground  drainage  is  in  the  southwestern  part  of  the  county.  It  is  an 
elongate,  rather  narrow  basin  between  Shetlerville  and  Eichorn,  its  extreme 
length  north  and  south  being  nearly  three  miles  and  its  width  about  one  mile. 
The  sink  through  which  the  drainage  of  this  area  passes  underground  is  in 
the  SW.  Vi  sec.  23,  T.  12  S.,  E.  7  E.^ 


CHAPTER  II— GEOLOGICAL  INTRODUCTION 

By  Stuart  Weller  and   Chas.   Butts 


The  rocks  which  constitute  the  earth's  crust  in  Hardin  County  and 
-elsewhere  throughout  the  earth,  are  of  two  sorts  as  regards  their  origin,  sedi- 
mentary and  igneous.  By  far  the  greater  part  of  these  rocks  is  sedimentary, 
this  class  including  the  sandstones,  limestones,  and  shales  ("slates"),  all  of 
which  lie  in  an  essentially  horizontal  position  or  are  locally  tilted  to  a  greater 
or  less  degree.  This  is  especially  true  of  Hardin  County,  where  the  igneous 
rocks  constitute  a  very  minor  portion  of  the  crust,  and  occur  in  the  form  of 
more  or  less  vertical  dikes,  or  as  sills  which  are  horizontal  expansions  from 
dikes. 

Sedimentary  Rocks 

The  sedimentary  rocks  of  the  region  have  all  been  formed  as  accumula- 
tions of  sand  or  mud  at  the  bottom  of  basins  filled  with  water,  or  on  the  flood 
plains  of  ancient  and  long  extinct  rivers.  The  limestones,  shales,  and  a  con- 
siderable portion  of  the  sandstones  were  accumulated  in  the  bottom  of  a  great 
embayment  of  an  ancient  ocean  which  covered  all  of  southern  Illinois,  and 
parts  or  the  whole  of  adjacent  states.  This  oceanic  embayment  was  essentially 
a  northward  extension  of  the  Gulf  of  Mexico.  These  sediments  are  known 
to  have  been  deposited  in  the  ocean  bottom  because  of  the  presence  in  them 
of  innumerable  examples  of  fossil  shells,  corals,  and  other  marine  organisms 
which  live  today  and  are  known  always  to  have  lived  under  conditions  fur- 
nished only  by  the  oceanic  waters.  Similar  deposits  are  being  formed  widely 
at  the  present  time  along  the  shores  of  the  ocean  as  it  now  exists.  All 
streams  which  drain  the  land  surfaces  transport  quantities  of  sediment  in  the 
form  of  sand  and  mud.  The  muddy  waters  of  the  streams  which  drain  Hardin 
County  after  heavy  rains,  the  muddy  waters  of  Ohio  River  at  flood  times,  and 
of  the  Mississippi  at  all  times,  are  due  to  the  suspended  particles  of  sand 
and  clay.  Further  evidence  of  the  transportation  of  this  material  is  found 
in  the  constant  changes  in  the  sand  bars  of  the  river.  At  all  times  to  some 
extent,  and  especially  during  seasons  of  flood,  these  materials  are  carried 
down  stream,  and  sooner  or  later  are  dumped  at  the  mouth  of  Mississippi 
River  where  they  help  to  build  up  the  great  delta  of  that  stream.  Thence, 
tbese  same  materials  are  reworked  over  and  over  again  by  action  of  the  ocean 
waves.  They  are  washed  alons:  the  shore  line-  and  assorted  into  coarser  and 
finer  materials;  the  sand  becomes  a  part  of  the  beach  sand  of  the  ocean  shore; 


24  GEOLOGY    OF    HARDIN    COUNTY 

the  finer  particles  of  mud  and  clay  are  held  in  suspension  and  are  finally 
allowed  to  settle  in  deeper  waters  off  shore  where  they  may  not  again  be 
disturbed. 

These  processes  which  are  taking  place  at  the  present  time  have  been  in 
progress  through  untold  ages.  During  much  of  the  time  while  the  sedi- 
mentary rocks  of  Hardin  County  were  forming,  the  shore  line  of  the  ancient 
ocean  crossed  Illinois  in  a  general  east-west  direction  near  the  center  of  the 
State.  This  shore-line  was  shifting  to  the  north  and  to  the  south,  however, 
from  time  to  time,  as  is  shown  by  the  varying  types  of  sediments  that  were 
deposited,  and  there  doubtless  were  periods  when  this  ocean  shore  crossed 
Hardin  County  itself. 

The  sediments,  laid  down  in  this  ancient  ocean  as  loose  sand  and  mud, 
gradually  became  consolidated  by  reason  of  the  great  weight  of  the  sediments 
themselves  which  were  piled  layer  upon  layer  for  several  thousands  of  feet, 
and  through  the  process  of  cementation  associated  with  the  percolation  of 
waters  through  the  more  or  less  porous  mass. 

As  they  were  originally  formed,  these  sedimentary  deposits  were  essentially 
horizontal,  although  there  must  have  been  a  gentle,  almost  imperceptible  slope 
or  dip  from  the  shore  line  through  the  shallow  to  the  deeper  waters  at  some 
distance  from  the  shore.  The  type  of  sediment  changed  with  changing  con- 
ditions. The  sands  were  deposited  at  such  times  as  the  rivers  emptying  into 
this  part  of  the  ocean  were  bringing  in  great  quantities  of  sand,  which 
accumulated  along  the  shore  and  in  the  comparatively  shallow  waters  near 
shore.  The  shallow  water  origin  of  practically  all  of  the  sandstones  of  the 
county  is  established  by  the  presence  of  buried  wave  and  ripple  marks  upon 
the  rock  surfaces  in  many  places.  These  marks  were  formed  by  the  undulating 
motion  of  the  waters  of  the  ancient  ocean,  just  as  similar  marks  are  formed 
today,  in  the  same  manner,  in  the  sand  along  the  shores  of  the  present  Ohio 
River.  Not  all  the  ripple-marks  formed  in  these  ancient  seas  have  been 
preserved  but  some  of  them  were  buried  beneath  fresh  layers  of  sand,  never 
to  be  disturbed  until  long  after  the  sediments  had  been  consolidated  into 
sandstones,  and  now  these  markings  are  not  infrequently  exposed  when  layers 
of  the  rock  are  split  apart.  The  phenomenon  of  cross-bedding  in  the  sand- 
stones, or  the  local  development  of  bedding  at  an  angle  to  the  position  of  the 
formation  as  a  whole,  is  another  evidence  of  shallow  water  origin  of  the 
sandstones.  Similar  phenomena  may  be  observed  today  in  the  sand-liars  of 
Ohio  River  as  well  as  in  oceanic  deposits. 

In  general  the  shales  and  limestones  of  the  county  were  deposited  in 
somewhat  deeper  waters  than  the  sandstones,  although  the  cutting  off  of  the 
supply  of  sands  by  the  streams  which  poured  their  waters  into  this  part  of  the 
ocean  permitted  the  deposition  of  shales  nearer  shore.  The  materials  con- 
stituting the  shales  were  supplied  in  the  same  manner  as  were  the  sands  for 


GEOLOGICAL   INTRODUCTION  ^5 

the  sandstone,  namely  through  the  transportation  agencies  of  streams  drain- 
ing the  surrounding  land  surface,  but  the  materials  were  finely  divided 
particles  of  clay  or  mud  instead  of  sand  grains.  In  places  there  was  an 
accumulation  of  a  mixture  of  clay  and  sand  from  which  have  arisen  some  of 
the  sandy  (arenaceous)  shales  of  the  county. 

The  limestones  had  a  totally  different  origin  from  the  sandstones  and 
shales.  They  were  formed  entirely  from  the  shells  and  other  hard  parts  of 
lime-secreting  animals  which  lived  in  the  ancient  ocean8.  In  many  places  in 
the  county  the  limestones  are  associated  with  or  are  interbedded  with  shale 
layers,  showing  that  the  depth  of  water  in  which  they  were  accumulated  was 
not  greater  than  that  in  which  the  shales  were  formed.  In  general  the  lime- 
stones were  deposited  in  somewhat  deeper  waters  than  the  sandstones,  but  if 
at  times  no  sand  was  being  dumped  into  the  ocean  basin  by  the  streams  from 
the  surrounding  land  surface,  the  accumulation  of  these  calcareous  materials 
might  have  taken  place  up  to  the  shore  line.  That  many  of  the  limestones 
of  the  region  actually  were  accumulated  in  shallow  waters  is  shown  by  the 
presence  of  conspicuous  cross-bedding  in  the  limestones  at  many  localities. 

The  several  layers  of  sedimentary  rocks,  limestone,  shale  ("slate"),  sand- 
stone, and  their  many  lithologic  variations,  constitute  the  formations  of  the 
geological  section  of  the  region.  These  lie  in  great  sheets  or  continuous 
blankets  called  strata,  that  vary  in  thickness  up  to  several  hundred  feet  and 
are  arranged  one  upon  another  like  the  successive  boards  in  a  pile  of  lumber. 
If  it  be  imagined  that  a  board  were  laid  down  each  day  for  30  days,  then  the 
board  at  the  bottom  might  be  regarded  as  the  oldest  and  that  at  the  top  the 
youngest  of  the  pile.  So  the  strata  of  rock  are  of  different  ages,  those  above 
being  younger  than  those  next  below. 

What  is  true  for  Hardin  County  is  true  for  the  whole  earth.  The  strata 
are  of  different  ages  and  each  group  of  strata  or  formation  usually  has  some 
mark  or  character  by  which  its  age  can  be  detei mined.  It  is  as  if  a  number 
of  layers  of  cement  were  laid  down  one  upon  the  other  on  successive  days  and 
each  layer  given  a  distinctive  color,  that  laid  down  on  the  fifth  day,  for 
example,  being  colored  red.  Then  if  the  layer  extended  over  several  counties 
and  could  be  seen  only  in  a  few  places  where  some  small  pait  of  it  had  been 
exposed  by  removing  the  overlying  layers  by  some  means,  as  rock  layers  are 
exposed  by  a  stream  and  are  shown  on  the  banks  of  a  river  or  on  the  sides  of 
a  ravine,  or  if  the  strata  should  be  penetrated  in  boring  a  well,  the  red  color 
would  show  on  which  day  that  particular  layer  was  laid  down.  In  other 
words,  if  the  succession  of  colors  were  known,  the  red  color  would  show  at 
once  the  relative  age  of  that  layer.  In  like  manner  each  rock  formation  of 
the  earth's  crust  has  its  particular  place  and  age  in  the  general  order  of  suc- 
cession of  layers  making  the  outer  crust,  and  commonly  it  has  some  mark  by 
which  its  age  and  position  in  the  whole  series  may  be  recognized. 


26  GEOLOGY    OF    IIAIiDIN    COUNTY 

The  most  reliable  age  marks  of  a  geological  formation  are  the  fossil  shells 
and  other  parts  of  animals  and  plants  found  imbedded  in  the  rocks.  These 
fossils  are  the  remains  of  organisms  that  were  actually  living  on  the  earth  at 
the  time  when  the  rock  strata  which  contain  them  were  being  formed.  The 
long  observations  of  geologists  have  shown  that  the  life  upon  the  earth  has 
been  continually  changing  progressively,  and  no  rock  formation  contains  a 
group  of  fossils  that  are  exactly  like  those  of  any  older  or  younger  formation. 
Because  of  this  established  fact  the  careful  gathering  and  study  of  collections 
of  fossils  is  a  very  important  part  of  a  geologist's  work. 

In  Hardin  County  the  determinable  fossils  are  mostly  confined  to  the 
limestone  and  shale  formations,  the  sandstones  in  general  being  poorly  adapted 
for  the  preservation  of  such  objects.  This  circumstance,  therefore,  shows  the 
great  importance  of  the  critical  examination  of  the  limestone  outcrops  of  the 
county,  for  in  many  cases  the  age  of  a  particular  sandstone  can  be  determined 
only  through  observation  of  its  stratigraphic  relations  with  some  limestone 
formation.  It  has  been  determined  through  careful  observation  and  study 
that  each  of  the  limestone  formations  in  the  stratigraphic  succession  of  the 
county  have  certain  distinctive  species  of  fossils  or  groups  of  fossils,  which  are 
designated  as  index  fossils.  These  are  the  fossils  commonly  to  be  searched  for 
in  the  rock  outcrops  for  the  purpose  of  determining  the  age  of  the  stratum 
exposed. 

Unconformities 

Frequently,  during  the  progress  of  geological  time,  and  in  many  places, 
there  have  been  interruptions  in  the  accumulation  of  the  sediments  which 
constitute  the  rocks  of  the  earth's  crust.  Such  interruptions  are  due  to  the 
changes  in  the  positions  of  the  ancient  shore  lines,  and  consequently  to  changes 
in  the  distribution  of  land  and  water.  Such  interruptions  may  have  been 
of  brief  duration,  or  they  may  have  extended  over  long  periods  of  time  during 
which  greater  or  less  thicknesses  of  sediments  were  accumulated  elsewhere- 
than  in  the  region  of  dry  land  under  consideration.  Such  breaks  in  the  strati- 
graphic succession  are  known  as  unconformities.  Criteria  for  the  recognition 
of  unconformities  are  of  various  sorts.  Where  a  period  of  deformation  has 
intervened  between  the  time  of  deposition  of  the  older  and  younger  strata,. 
during  which  the  older  beds  were  tilted  or  folded,  the  lack  of  parallelism 
between  the  strata  on  the  two  sides  of  the  stratigraphic  break  shows  an 
unconformity.  In  a  large  number  of  cases,  however,  and  in  all  cases  in  Hardin 
County,  the  strata  below  and  above  the  recognized  unconformities  are  essen- 
tially  parallel.  Under  such  circumstances  an  abrupt  change  in  the  character 
of  the  sediments,  as  from  a  limestone  to  a  sandstone,  may  indicate  uncon- 
formable relations.  Very  commonly  the  surface  of  the  underlying  formation 
is  more  or  less  uneven,  showing  the  results  of  weathering  or  erosion  during 


GEOLOGICAL  INTRODUCTION  27 

the  time  represented  by  the  unconfoimity,  and  in  some  cases  the  surface 
beneath  the  unconformity  exhibits  distinct  evidence  of  oxidization  that  took 
place  preceding  the  deposition  of  the  higher  formation.  Not  infrequently  the 
basal  portion  of  the  formation  overlying  an  unconformity  is  characterized  by 
a  conglomeratic  layer  called  a  basal  conglomerate,  in  which  there  are  pebbles 
that  have  been  derived  from  older  formations. 

Geologic  Time 

Geologic  time,  that  is  the  time  during  which  the  earth  has  been  brought 
into  its  present  form,  physically  and  geographically,  from  its  primitive  con- 
dition, is  inconceivably  long.  The  records  of  the  sequence  of  events  in  the 
earth's  history  have  been  preserved  in  the  rocks  which  constitute  the  earth's 
crust,  and  it  is  the  task  of  the  geologist  to  interpret  this  history  from  the 
available  records. 

Just  as  our  year  is  divided  into  the  seasons,  Spring,  Summer,  Autumn, 
and  Winter,  and  just  as  the  history  of  our  country  is  divided  into  more  or 
less  sharply  denned  periods,  such  as  the  "Colonial  period,"  the  "Revolu- 
tionary period,"  or  the  "Civil  War  period,"  so  geologic  time  is  divided  into 
a  series  of  major  periods.  Geologic  time  has  continued,  of  course,  without 
interruption  and  without  break,  just  as  the  days  of  the  year  follow  each  other 
in  unbroken  succession,  and  just  as  the  years  of  our  national  history  have 
followed  uninterruptedly.  However,  from  a  study  of  the  rocks,  geologic 
history  can  be  divided  into  just  as  distinctly  different  periods  as  are  the 
seasons  of  the  year  or  the  epochs  of  our  national  history. 

All  the  rocks  of  the  outer  crust  of  the  earth  are  divided  and  subdivided 
into  units  of  different  orders  called  members;  or  forum t ion*  including  one 
or  more  members;  or  groups  made  up  of  one  or  more  formations;  or  systems 
including  one  or  more  groups.  The  time  corresponding  to  two  or  more 
systems  is  called  an  era,  the  time  corresponding  to  a  single  system  is  called 
a  period,  and  that  corresponding  to  a  group  or  to  a  formation  is  called  an 
epoch.  The  eras  are  named  from  the  stage  in  the  progress  of  life  upon  the 
earth.  The  Proterozoic  was  the  time  of  primitive  life.  The  Paleozoic  era 
means  the  era  of  ancient  life,  invertebrate  animals  predominating;  Mesozoic 
era  means  the  time  of  middle  life,  great  reptiles  predominating;  and  the 
Cenozoic  era  means  the  era  of  recent  life,  the  mammals,  to  which  man  belongs, 
predominating.  Geologists  have  commonly  recognized  fourteen  periods  pre- 
ceding recent  time,  which  are  grouped  under  the  four  larger  eras  that  have 
been  mentioned,  as  follows: 


28 


GEOLOGY    OF    HARDIN    COUNTY 
Table  of  Geologic  Time  Divisions 


Era 


Cenozoic 


Period 


Quaternary 
Tertiary 


Mesozoic 


Cretaceous 
Jurassic 


Triassic 

Permian 

Pennsylvanian 

Mississippian 

Paleozoic 

Devonian 
Silurian 
Ordovician 
Cambrian 

Proterozoic 

Algonkian 
Archean 

The  geologic  record  in  Proterozoic  or  pre-Cambrian  time  is  much  less 
definite  than  is  that  of  the  periods  from  Cambrian  to  Recent,  and  it  is  only 
in  the  Cambrian  that  we  find  the  first  fairly  complete  record  of  the  life  of  the 
earth,  the  pre-Cambrian  rocks  being  so  highly  metamorphosed  or  changed 
that  the  fossil  forms  they  may  have  held  originally  have  been  destroyed  for 
the  most  part.  Consequently  the  relative  ages  of  those  rocks  cannot  be  so 
readily  determined  as  can  the  ages  of  the  later  formations. 

The  actual  time  that  has  elapsed  since  the  beginning  of  the  Cambrian 
period  can  be  estimated  only  in  the  roughest  sort  of  way.  Estimates  have 
been  attempted  by  a  number  of  geologists,  and  have  ranged  from  thirty  to 
several  hundred  million  years.  From  seventy-five  to  one  hundred  million 
years  may  be  assumed  as  a  conservative  estimate  of  this  time,  but  the  im- 
portant thought  to  be  held  in  mind  in  this  connection  is  not  the  number  of 
years  involved,  but  that  the  time  is  enormously,  inconceivably  long. 

In  Hardin  County  all  of  the  hard  rocks  exposed  at  the  surface  are 
referable  to  the  Devonian,  Mississippian,  and  Pennsylvanian  periods.  These 
are  undoubtedly  underlain  by  rocks  of  the  older  periods,  but  no  deep  drilling 
has  ever  been  done  in  the  county  which  can  give  us  any  information  in  regard 
to  them.  In  addition  to  the  hard  rock  formations,  there  are  the  unconsolidated 
surfieial  materials  which  are  for  the  most  part  of  Pleistocene  age,  the  period 
immediately  preceding  Recent  time  in  the  Quaternary. 


GEOLOGICAL  INTRODUCTION  2U 


Igneous  Rocks 


As  has  already  been  indicated  the  igneous  rocks  of  Hardin  County  con- 
stitute a  very  minor  portion  of  its   surface.     They  were  originally   in  the 
condition  of  molten  rock  or  lava,  that  is  in  a  more  or  less  liquid  state  at  a 
high  degree  of  temperature.     A  great  mass  of  this  molten  material  was,  at 
one  time  in  the  history  of  the  earth,  intruded  or  forced  by  some  great  internal 
pressure  into  and  beneath  the  sedimentary  rocks  of  the  region.     It  is  not  im- 
probable that  the  bowing  up  of  the  rock  strata  to  form  the  Hicks  dome  was 
due  to  such  a  deep  seated  intrusion.    In  the  process  of  this  intrusion  the  rocks 
overlying  the  intruded  mass  were  cracked  in  places  and  the  liquid  or  pasty 
material  of  the  intrusion  was  squeezed  up  into  the  cracks,  eventually  becoming 
solidified  on  cooling  and  so  healing  the  cracks  that  had  been  formed,  with 
material   fully   as   dense   and   hard   as   the   material   constituting  the   rocks 
through  which  the  cracks  had  originally  passed.     These  igneous  rocks,  which 
may  now  be  seen  at  a  number  of  places  in  the  county,  are  dark  in  color,  in 
pome  places  nearly  black,  elsewhere  a  little  greenish  or  of  a  gray  tint.     In 
most  exposures  the  igneous  rocks  occur  as  nearly  vertical  bands  known  as 
dilces,  from  one  foot  or  less  to  one  hundred  feet  or  more  in  width.  ^  At  one 
locality  the  igneous  material  has  spread  out  horizontally  in  a  bed  of  limestone 
about  four  feet  thick,  the  intruded  rock  occurring  in  stringers  from  a  small 
fraction  of  an  inch  in  thickness  to  layers  three  or  four  inches  thick.     These 
intruded  bands  for  the  most  part  follow  the  bedding  planes  in  the  limestone 
layer,  but  at  intervals  they  break  across  the  bedding  planes  in  more  or  less 
oblique  directions.     Such  a  horizontal  intrusion  of  igneous  rock  is  known  as 
a  sill  and  must  somewhere  be  connected  with  a  dike  which  served  as  its  feeder. 

Geologic  Structure 

The  original  position  of  the  sedimentary  rocks  in  the  earth's  crust  was 
essentially  horizontal,  each  unit  in  the  section  consisting  of  a  continuous 
blanket-like  formation  throughout  an  area  of  greater  or  less  extent.  In  many 
parts  of  the  country  the  rocks  still  retain  their  original  horizontal  position, 
but  throughout  Hardin  County  they  have  been  greatly  disturbed  and  are  now 
neither  entirely  horizontal  nor  continuous.  The  present  lay  and  arrangement 
of  the  formations  and  the  features  resulting  from  their  production  constitute 
what  is  termed  the  geologic  structure. 

The  structures  in  Hardin  County  are  of  two  sorts.  In  one  part  of  the 
county,  with  Hicks  as  a  center,  the  rock  strata  have  at  some  time  in  their 
history  been  bowed  up  into  a  dome,  from  the  center  of  which  they  now  dip 
or  slope  away  in  all  directions.  It  is  not  unlikely  that  the  Hicks  dome  was 
formed  through  the  agency  of  a  deep  seated  intrusion  of  molten  igneous 
material,  which  lifted  the  entire  thickness  of  overlying  strata  into  the  dome 


30  GEOLOGY    OF    HARDIN    COUNTY 

structure  which  they  now  exhibit.  Elsewhere  in  the  county,  and  not  directly 
associated  with  the  Hicks  dome,  the  rock  strata  exhibit  dips  of  greater  or  less 
degree  at  many  localities,  these  dips  being  associated  with  another  structural 
condition  known  as  faulting. 

The  phenomenon  of  faulting  as  exhibited  in  Hardin  County  and  else- 
where, involves  the  formation  of  more  or  less  vertical  or  oblique  cracks  in  the 
earth's  crust,  extending  to  unknown  depths,  and  the  slipping  of  the  rock 
strata  on  either  side  of  the  cracks  either  vertically,  or  horizontally,  or  in  both 
directions.  Such  dislocations  in  the  rock  strata  are  known  as  faults.  In  all 
faults,  except  where  the  motion  is  entirely  horizontal,  the  rock  strata  on  one 
side  of  a  fault  are  raised  relative  to  the  beds  on  the  opposite  side,  the  side 
which  is  raised  being  known  as  the  upthrow  side,  the  opposite  as  the  down- 
throw side  of  the  fault.  The  forces  in  the  earth's  crust  which  produce  faulting 
are  either  in  the  nature  of  compression  or  tension.  When  a  segment  of  the 
earth's  crust  is  for  some  reason  squeezed  between  two  adjacent  segments,  and 
the  compression  so  exerted  is  continued  beyond  the  resisting  power  of  the 
rock  formations  of  the  segment,  these  strata  must  give  way.  The  beds  will 
either  be  forced  into  folds  similar  to  the  bending  of  corrugated  sheet  iron, 
or  cracks  will  be  formed,  the  mass  on  one  side  of  the  crack  being  forced  up- 
ward and  over  the  mass  on  the  opposite  side,  along  a  more  or  less  oblique 
plane.  Such  a  fault  is  known  as  a  thrust  fault  or  a  reverse  fault.  In  many 
places  folds  pass  laterally  into  thrust  faults,  and  very  commonly  thrust  fault- 
ing is  associated  with  very  steeply  dipping  beds  which  are  not  infrequently 
overturned.  In  the  case  of  thrust  faulting  the  hanging  wall  is  always  the 
upthrow  side,  as  is  shown  in  the  accompanying  diagram  (fig.  1,  A)  and  the 
segment  of  the  earth's  crust  involved  is  shortened.  In  Hardin  County  none 
of  the  faulting  exhibited  is  of  the  thrust  type. 

A  second  type  of  faulting  is  produced  by  the  exertion  of  a  tension  or 
stretching  force  in  the  earth's  crust  rather  than  a  compression  or  squeezing 
force.  When  such  a  force  is  exerted  upon  the  rocks,  many  irregular  cracks 
are  likely  to  be  former!,  the  major  ones  of  which  will  have  a  general  direction 
at  right  angles  to  the  direction  of  the  tension  force.  The  rocks  will  give  way 
in  the  weakest  place,  which  may  be  a  belt  of  considerable  width,  in  which  the 
cracks  may  outline  a  regular  mosaic  of  blocks  of  various  sizes  and  shapes. 
The  blocks  so  formed  will  slip  downward  and  may  tip  upon  each  other  and 
finally  come  to  rest  when  the  tension  force  has  been  relieved.  Faulting  of 
this  sort  is  called  normal  faulting,  the  fault  planes  are  commonly  more  nearly 
vertical  than  in  reverse  faults,  and  the  hanging  wall  is  always  the  downthrown 
side  (fig.  1,  B). 

In  any  given  area  of  faulting  the  immediate  reason  for  the  forces  which 
have  produced  the  faults  cannot  always  be  determined.  In  all  cases,  however, 
the  development  of  these  forces  must  be  due  to  internal  or  surficial  changes 


GEOLOGICAL  INTRODUCTION 


31 


in  the  earth's  crust,  some  of  these  changes  being  in  the  nature  of  transfer  of 
materials  from  one  position  to  another,  either  on  the  earth's  surface  through 
the  processes  of  erosion,  or  internally  through  the  movement  of  masses  of 
molten  material.  Changes  in  temperature  of  parts  of  the  interior  of  the  earth 
are  also  effective  in  producing  cumulative  forces  which  may  result  in  faulting, 
as  also  will  the  action  of  gravity  upon  certain  segments  of  the  crust  which 
are  heavier  than  others. 


Hanging  wall 


Hanging  wall 


Fig.  1. — A.     Diagram  to  show  the  movement  of  rock  strata  in  reverse  faulting. 
B.     Diagram  to  show  the  movement  of  rock  strata  in  normal  faulting. 


Dip  and  Strike 

The  term  dip  is  applied  to  rock  formations  to  indicate  the  inclination  of 
the  strata  (fig.  2).  The  degree  of  dip  is  expressed  by  the  angle  included 
between  the  surface  of  the  rock  stratum  and  a  horizontal  surface  that  intersects 
it.  Thus,  if  the  strata  themselves  are  horizontal,  the  dip  is  0°,  or  if  the  strata 
are  vertical  the  dip  is  90°  ;  any  intermediate  degree  of  inclination  or  dip  may 
be  present.  There  are  localities,  but  not  in  Hardin  County,  where  strata  are 
inclined  even  more  than  90°  and  are  said  to  be  overturned,  but  such  conditions 


32 


GEOLOGY    OF    IIAKDIN    COUNTY 


are  associated  with  thrust  faulting  which  is  not  the  type  of  faulting  exhibited 
here.  The  direction  of  the  dip  is  said  to  be  along  the  downward  slope  of  the 
beds.  The  term  strike  is  applied  to  the  line  of  intersection  between  a  dipping 
rock  surface  and  a  horizontal  plane  (fig.  2).  This  line,  then  is  always  at 
right  angles  to  the  dip,  and  its  direction  is  indicated  by  reference  to  the 
cardinal  points  of  the  compass.  In  situations  where  the  surface  of  dipping 
strata  is  plane,  the  strike  lines  are  straight,  but  if  the  dipping  strata  are 
warped,  the  strike  will  be  along  curved  lines.  Observations  upon  the  dip  and 
strike  of  rock  formations  are  of  great  importance  in  working  out  the  geologic 
structure  of  a  region.  Upon  the  geologic  map  (PL  I)  an  appropriate  symbol 
is  used  to  indicate  dip  and  strike,  a  short,  arrow-pointed  line  being  directed 


iv0 


VV     '„:   rfff 


Fig.  2.— Diagram  illustrating  the  structural  terms  "dip"  and  "strike." 

down  the  dip,  and  a  longer  line  at  right  angles  to  the  other  being  placed  in 
the  direction  of  the  strike. 


Topographic  Development 

Contrary  to  the  common  conception  of  persons  without  geological  ex- 
perience, the  topography  of  a  region,  that  is  the  irregularities  of  the  surface, 
the  hills,  the  valleys,  the  plains,  are  not  unchangeable.  The  "everlasting- 
hills"  are  a  myth,  for  every  season  brings  about  some  changes,  however  small. 
The  most  notable  changes  in  topographic  form  are  produced  through  the 
agencies  of  weathering,  wind,  and  stream  erosion.  The  rocks  which  are 
exposed  at  the  surface  or  which  are  so  situated  that  they  come  in  contact  with 
underground   waters,   are  constantly   being  subjected   to   changes   of   various 


GEOLOGICAL    INTRODUCTION  33 

sorts.  Limestones  are  slightly  soluble  in  ordinary  ground  waters.  The 
"hard  water"  of  springs  coming  from  the  limestone  possesses  that  character 
because  of  the  lime  that  is  held  in  solution.  It  is  common  experience  that 
constant  use  of  such  water  in  cooking  utensils  where  the  water  is  boiled,  causes 
a  scale  of  lime  to  form  upon  the  inner  surface  of  the  vessels.  This  is  the 
lime  residuum  from  the  evaporation  of  the  water  by  boiling.  Springs  from 
sandstone  formations  have  a  very  different  quality  of  water  than  limestone 
springs.  Such  water  is  "soft"  because  no  lime  is  present  in  solution.  Although 
ground  water  will  hold  but  a  small  amount  of  lime  in  solution,  yet  by  long 
continued  action  of  such  water  upon  limestone  formations,  great  quantities 
of  material  are  removed  and  all  the  sink  holes,  caves,  and  solution  channels 
of  limestone  formations  are  so  formed.  The  greater  solubility  of  limestone 
as  compared  with  other  rocks,  is  responsible  for  the  fact  that  limestone 
boulders  are  much  less  commonly  met  with  upon  the  surface  of  the  ground 
and  in  the  debris  of  creek  beds,  than  is  sandstone.  In  many  places  in  Hardin 
County  and  elsewhere,  where  the  geologist  is  certain  that  limestone  is  present, 
the  surface  of  the  ground  may  exhibit  nothing  but  broken  masses  of  sandstone. 
The  solution  of  rock  materials  by  underground  and  running  waters  is  not 
the  onty  means  by  which  the  materials  of  the  earth's  crust  are  removed  from 
one  place  and  carried  to  another ;  in  fact  this  agency  is  responsible  for  far  less 
of  the  work  than  is  erosion.  Erosion  is  the  term  applied  to  the  processes  of 
wearing  away  of  the  rocks  of  the  earth's  crust  through  the  agency  of  running 
water,  ice,  or  air.  Water  is  and  has  been  by  far  the  most  efficient  agent  of 
erosion  in  such  a  region  as  Hardin  County.  In  the  process  of  erosion  there 
are  three  different  functions  performed  by  the  moving  Avater.  The  first  of 
these  is  the  wearing  away  or  removal  of  rock  fragments  from  their  position 
as  portions  of  the  rock  formations  in  place.  This  may  be  accomplished  either 
through  the  force  of  the  moving  water  itself  in  plucking  rock  fragments  from 
their  position  along  its  path,  or  through  the  agency  of  materials  held  in  sus- 
pension  in  the  water.  It  is  common  experience  that  a  hand  full  of  sand,  when 
rubbed  forceably  upon  the  surface  of  a  dirty  or  corroded  piece  of  metal,  is 
efficient  in  the  removal  of  the  dirt  or  rust.  In  the  same  manner  sand  particles, 
as  well  as  rock  fragments  of  larger  size,  when  held  in  suspension  in  moving 
water,  will  remove  particles  of  the  rock  surface  over  which  the  water  passes. 
The  second  function  of  the  moving  water  is  the  transportation  of  materials. 
The  muddy  waters  of  swollen  streams  are  sufficient  evidence  of  this  transportive 
power.  Every  grain  of  sand,  and  every  particle  of  mud  has  at  some  time  been 
a  constituent  part  of  a  solid  rock  formation.  Swiftly  flowing  streams  are 
capable  of  moving  large  boulders,  and  rock  fragments  of  all  intermediate  sizes 
between  such  masses  and  sand  grains,  and  moving  water  is  constantly  carrying 
rock  fragments  of  all  sizes  down  grade.  The  moving  rock  masses  in  a  stream 
bed  are  constantly  bumping  against  each  other  as  they  progress  down  stream, 
—3  G 


34  GEOLOGY  OF  HARDIN  COUNTY 

chipping  and  wearing  small  particles  from  each  other  as  they  move  along,  this 
being  the  reason  for  the  rounded  forms  of  stream  boulders  as  compared  with 
those  lying  upon  hill  sides.  The  third  function  of  water  in  the  process  of 
erosion  is  the  deposition  of  materials.  The  ability  of  water  to  transport 
material  is  dependent  upon  the  rate  of  its  motion.  A  swiftly  moving  stream 
can  carry  more  and  larger  rock  fragments  than  a  quiet  stream.  Consequently 
if  the  rate  of  motion  of  a  stream  is  reduced  it  must  deposit  part  of  its  load, 
and  if  the  water  becomes  entirely  quiet  it  must  eventually  drop  the  whole  of 
its  load,  although  the  fine  particles  of  mud  may  be  held  in  suspension  for  a 
long  time. 

When  we  think  of  the  actual  work  that  is  being  done  by  the  streams  in 
such  a  region  as  Hardin  County,  exhibited  with  every  hard  rain,  we  realize 
that  there  is  a  constant  movement  of  the  materials  of  the  earth's  crust  down 
the  slopes.  Then  when  we  combine  this  thought  with  our  conception  of  the 
inconceivably  long  geologic  time,  we  can  realize  that  the  amount  of  work 
which  may  be  accomplished  in  the  sculpturing  of  the  earth's  surface,  is  prac- 
tically limitless.  Geologists  are  agreed  that  all  of  the  topographic  forms  as 
they  now  exist  in  such  an  area  as  Hardin  County,  are  due  to  the  work  of  the 
streams  which  are  present  in  the  area.  Through  countless  ages  the  water  has 
been  falling  as  rain  and  has  run  off  down  the  slopes,  continually  shifting 
material  downward,  until  all  the  hills  and  valleys  as  we  know  them  have  been 
carved  out. 

There  are  other  processes  that  have  served  in  a  notable  degree  to  prepare 
the  materials  to  be  removed  from  one  place  to  another.  These  processes  come 
under  the  general  head  of  weathering.  Plants  growing  upon  rock  may  send 
their  roots  into  crevices,  and  by  continued  growth  force  off  small  rock  particles 
which  may  be  carried  away  by  moving  water.  Decaying  vegetation  may 
generate  organic  acids  which  act  upon  the  constituent  materials  of  solid  rock, 
loosening  the  fragments  of  the  rock  and  causing  it  to  crumble  to  such  a 
condition  that  the  particles  may  be  removed  by  moving  water.  Water  may 
penetrate  the  cracks  in  the  rock,  and  on  freezing  expand  sufficiently  to  be  an 
effective  agent  in  fracturing  the  solid  rock  masses.  The  agencies  of  weather- 
ing are  acting  constantly  and  tend  to  break  down  the  solid  rock  masses  into 
fragments  which  can  be  handled  by  the  moving  water. 

The  several  types  of  rocks  vary  in  their  powers  of  resistance  to  the  various 
processes  of  weathering  and  erosion.  Softer  rocks  are  much  more  easily 
broken  down  and  carried  away  than  the  harder  ones,  and  limestones,  because 
of  their  solubility,  are  less  resistant  than  sandstones.  For  this  reason  the  less 
easily  decomposed  or  harder  rocks  commonly  constitute  the  higher  ground; 
nearly  all  the  hills  in  Hardin  County  are  capped  with  sandstone,  while  the 
limestone  and  shales,  where  present,  commonly  outcrop  on  the  slopes  below 
the  sandstones. 


GEOLOGICAL  INTRODUCTION  35 

The  accumulations  of  irregular,  broken  fragments  of  rocks,  mixed  with 
soil  and  other  finer  material,  which  gather  at  the  base  of  rocky  bluffs  or  steep 
hillsides,  are  termed  talus  deposits.  These  talus  accumulations  are  so  ex- 
tensive in  places  that  they  effectually  obscure  the  rock  strata  which  constitute 
the  lower  portion  of  the  hill  or  bluff  against  which  they  lie.  In  situations 
where  a  bluff  consists  of  a  massive  sandstone  above,  and  a  softer,  perhaps 
shale  or  limestone  formation  below,  the  lower  formation  furnishes  an  insecure 
support  for  the  higher  sandstone,  and  the  resulting  talus  is  likely  to  include 
great  slumped  masses  of  sandstone,  some  of  which  may  be  many  cubic  yards 
in  extent. 

In  the  course  of  its  topographic  development  every  area  passes  through 
one  or  more  cycles  of  erosion,  These  cycles  of  erosion  may  be  completed  or 
they  may  be  interrupted  in  the  course  of  their  history  in  such  a  manner  that 
a  new  cycle  is  initiated  before  the  older  one  has  been  finished.  The  history 
of  a  complete  cycle  of  erosion  involves  the  uplift  or  elevation  of  a  given 
region,  followed  by  the  wearing  down  of  the  uplifted  surface  through  the 
agency  of  the  streams  that  are  developed  upon  its  surface.  At  the  time  of 
their  initiation  upon  a  surface  newly  raised  from  beneath  the  sea  where  no 
stream  channels  have  been  present  previously,  the  paths  to  be  followed  by 
waters  which  fall  as  rain,  will  be  along  the  lines  of  least  resistance.  There  are 
.likely  to  be  some  unevenesses  in  the  surface  which  may  control  the  run-off  of 
water  falling  as  rain,  and  in  whatever  position  the  streams  begin  their  work, 
there  in  general  they  will  continue  to  carry  it  on  throughout  their  history, 
except  as  they  are  influenced  by  the  varying  hardness  of  the  rocks  and  the 
geologic  structure. 

When  first  uplifted,  either  from  beneath  the  sea  or  from  the  position  of 
a  low-lying  plain,  the  land  surface  wtll  be  comparatively  level;  then  the 
streams  will  dissect  the  area  into  valleys  and  ridges;  and  as  erosion  is  con- 
tinued the  hills  and  ridges  themselves  will  be  gradually  reduced,  provided  the 
region  is  not  re-elevated,  until  finally  an  approximately  plane  surface  at  or 
near  sea-level  is  again  produced.  An  area  which  passes  through  all  these 
stages  completes  a  full  cycle  of  erosion,  and  the  topographic  development  is 
said  to  be  youthful,  mature,  or  old,  depending  upon  whether  it  represents  an 
earlier  or  later  stage  in  the  accomplishment  of  the  erosion  cycle.  In  the  stage 
of  youthful  topography  the  drainage  is  not  yet  fully  established,  parts  of  the 
area  may  be  undrained,  and  the  surface  relief  or  the  difference  between  the 
high  and  low  spots  is  not  great.  In  the  stage  of  mature  topography,  drainage 
lines  are  fully  established;  they  have  cut  deeply  into  the  surface  to  be  drained; 
the  hills  are  narrow  ridges  which  rise  to  elevations  approximating  the  position 
of  the. original  altitude  of  the  surface  during  youth;  and  the  surface  relief  is 
great.  In  old  age  topography  the  surface  relief  is  reduced  so  that  the  area 
approximates  a  plane ;  and  a  few  main  drainage  lines  are  present  which  serve 


3G  GEOLOGY    OE    HARDIN    COUNTY 

as  trunk  lines  to  carry  off  the  waters  which  fall  upon  the  surface.  Of  course, 
in  the  topographic  history  of  any  region  there  are  no  hard  and  fast  lines 
between  the  several  stages;  youthful  topography  gradually  passes  into  ma- 
turity, and  that  into  old  age,  just  as  a  man  passes  by  gradual  changes  from 
youth  to  middle  age  and  then  into  old  age.  The  topographic  development  in 
Hardin  County  is  in  the  stage  of  maturity. 

Geological  Map 

A  proper  geological  map  of  any  region  must  be  drawn  upon  a  topographic 
base  map.  The  topographic  maps  constructed  by  the  Illinois  State  Geological 
Survey  in  cooperation  with  the  U.  S.  Geological  Survey,  are  drawn  on  the 
scale  of  approximately  one  inch  to  the  mile,  that  is,  one  inch  on  the  map 
represents  one  mile  of  actual  land  surface.  Upon  this  map  all  the  cultural 
features,  such  as  roads,  railroads,  houses,  and  towns  are  accurately  located  and 
printed  in  black.  All  the  water,  creeks,  rivers,  swamps,  ponds,  and  lakes 
are  accurately  mapped  and  printed  in  blue.  The  more  or  less  sinuous  brown 
lines  which  cover  the  map  are  known  as  contour  lines,  and  their  purpose  is  to 
represent  the  topographic  form  of  the  area  mapped.  Each  point  upon  any  one 
contour  line  crossing  the  map  has  the  same  elevation  above  sea  level,  and  on 
the  map  of  Hardin  County  these  lines  are  drawn  to  represent  vertical  intervals 
of  twenty  feet.  Every  fifth  line  is  shown  a  little  heavier  than  the  intervening 
ones,  the  heavier  lines  being  the  contours  with  elevations  of  even  hundreds  of 
feet  above  sea  level.  The  proper  elevation  of  these  heavier  contours  is  indi- 
cated by  numbers  placed  at  convenient  distances  on  the  lines,  and  the  elevation 
of  the  intervening  contours  can  be  easily  calculated  wherever  it  is  desired, 
from  the  indicated  elevations  of  the  heavier  lines.  With  this  system  of 
mapping  it  will  be  seen  at  once  that  the  entire  surface  of  the  country,  with 
all  its  irregularities  can  be  accurately  shown.  Where  the  contour  lines  are 
close  together  the  hill  slope  represented  is  steep.  Where  the  land  surface  is 
more  nearly  level  the  contours  are  far  apart.  Such  a  map,  when  accurately 
constructed,  can  be  made  to  show  the  details  of  surface  configuration,  the 
shape  and  elevation  of  every  hill,  the  form  of  every  valley  and  ravine.  How- 
ever, the  accuracy  of  the  detail  of  such  a  map  is  directly  dependent  upon  the 
scale  adopted,  and  on  the  scale  of  one  inch  to  the  mile  less  detail  can  be  shown 
than  on  a  larger  scale. 

Upon  the  topographic  map  as  a  base,  the  geology  of  the  county  is  shown 
by  means  of  different  colors  or  by  patterns  and  shades  of  color,  which  indicate 
the  areas  in  which  the  several  geological  formations  which  have  been  recognized 
form  the  underlying  rock.  The  rock  formations  are  not  everywhere  exposed; 
if  they  were  the  county  would  of  course  be  worthless  for  agricultural  purposes. 
But  numerous  outcrops  are  present,  and  from  these  observed  outcrops  it  is 
possible  to  determine  with  approximate  accuracy  the  area  underlain  by  the 


GEOLOGICAL    INTRODUCTION  37 

formation.  The  continuous  surface  existing  between  two  formations  lying  in 
contact,  one  above  the  other,  may  be  termed  the  inter-formational  surface; 
and  the  boundary  lines  between  the  formations,  as  indicated  on  the  map,  then 
represent  the  intersections  of  these  inter-formational  surfaces  with  the  topo- 
graphic surface.  The  positions  of  the  inter-formational  surfaces  cannot  every- 
where be  seen,  but  the  geologist  can  determine  them  for  considerable  areas 
from  the  observation  of  comparatively  few  actual  outcrops.  If  the  formations 
in  any  region  lie  in  a  perfectly  horizontal  position,  the  inter-formational 
surfaces  will  intersect  the  topographic  surface  along  or  parallel  to  contour 
lines,  but  if  the  rock  formations  are  inclined,  then  the  intersection  between 
the  two  surfaces  will  cut  obliquely  downward  across  the  contours  in  the 
direction  of  the  clip  or  inclination,  while  in  the  direction  of  the  strike,  at  right 
angles  to  the  dip,  the  same  line  will  coincide  with  or  parallel  the  contours. 
Wherever  the  rock  formations  have  been  subjected  to  notable  deformation, 
such  as  folding  and  faulting,  the  intersections  between  the  inter-formational 
surfaces  and  the  topographic  surface  become  progressively  complicated. 

The  faults"  which  have  been  detected  in  Hardin  County  are  indicated 
upon  the  geological  map  by  continuous  black  lines.  They  are  characterized  by 
abrupt  changes  on  opposite  sides  of  the  lines,  of  the  positions  of  the  forma- 
tional  boundaries,  these  changes  being  due,  of  course,  to  the  relative  dislocation 
of  the  rocks  on  the  two  sides  of  the  fault. 


CHAPTER  III— GENERAL  GEOGRAPHY 

By    Rollin   D.  Salisbury 


Relief  and  Prevalent  Topography 

As  has  been  said  in  the  preceding  chapters,  the  surface  of  Hardin  County 
is  one  of  strong  relief.  Its  highest  point — on  the  north  line  of  the  county 
where  it  passes  near  the  crest  of  High  Knob — is  900  feet  above  the  sea.  Its 
lowest  point,  on  Ohio  River  at  the  southwest  corner  of  the  county,  is  between 
300  and  320  feet  above  the  sea.  The  total  relief  therefore  is  more  than  580  but 
less  than  600  feet. 

Great  as  this  relief  is,  the  mere  statement  of  the  range  of  elevations  gives 
no  adequate  picture  of  the  real  character  of  the  surface.  Its  most  notable 
feature  is  its  roughness,  and  the  dominant  type  of  roughness  is  that  produced 
by  the  erosion  of  running  water.  In  almost  every  direction  from  almost  any 
point,  hills  and  ridges  alternate  with  valleys.  Tributary  to  the  Ohio,  with  its 
deep  valley  on  the  south,  and  to  the  Saline,  with  its  almost  equally  deep  valley 
on  the  northeast,  are  numerous  creeks.  As  has  been  pointed  out,  eight  of 
these  are  large  enough  to  receive  names  on  the  map,  and  the  number  of 
smaller  creeks,  some  of  them  intermittent  only,  is  still  larger.  To  the  valleys 
of  all  these  creeks  there  are  tributary  valleys,  and  each  of  the  larger  ones  has 
numerous  tributaries.  Not  only  this,  but  five  creeks  large  enough  to  have 
names,  and  several  smaller  ones,  leave  the  county  on  the  west,  joining  Big 
Grand  Pierre  Creek  which  flows  to  the  Ohio  in  Pope  County;  and  as  many 
as  seven  creeks,  large  and  small,  flow  across  the  northern  border  of  the  county 
into  Gallatin  County.  Big  Creek  and  its  tribuaries  extend  almost  across  the 
county  from  north  to  south,  and  everywhere  in  the  county  the  heads  of  the 
tributaries  of  one  creek  system  are  near  the  heads  of  the  tributaries  of  another 
system.  All  told,  there  are  not  less  than  a  hundred  drainage  depressions  in 
the  county  which  might  be  called  valleys.  A  very  much  larger  number  of 
smaller  drainage  depressions,  which  perhaps  should  be  called  ravines  rather 
than  valleys,  are  tributary  to  the  larger  ones.  It  will  be  seen  that  when  these 
hundreds  of  drainage  lines,  large  and  small,  are  crowded  into  an  area  of  170 
square  miles,  there  can  be  little  surface  not  closely  adjacent  to  them.  Most 
of  the  surface  slopes  to  some  one  of  them.  So  thoroughly  is  the  surface  of 
the  upland  dissected  by  the  valleys  that  fully  9/10  of  the  surface  of  the 
county  has  distinct  slope. 

39 


40  GEOLOGY    OF    HARDIN    COUNTY 

At  their  lower  ends,  the  valleys  of  the  tributary  streams  are  about  as  low 
as  the  valleys  of  the  Ohio  and  the  Saline  respectively.  The  many  tributaries 
of  the  creeks  which  join  the  rivers  have  valleys  whose  depths  are  in  harmony 
with  those  of  the  streams  to  which  they  flow.  Most  of  the  valleys  are  100  to 
200  feet  deep,  but  some  of  them  are  as  much  as  300  feet  deep.  Such  relief 
alone,  of  course,  does  not  make  a  mountainous  country,  but  the  slopes  of 
many  mountain  regions  are  no  steeper  than  many  of  the  slopes  of  this  county. 

Since  most  of  the  valleys  are  narrow  as  well  as  deep,  it  follows  that  their 
slopes  are  so  steep  that  few  roads  ascend  or  descend  them  at  right  angles  to 
the  axes  of  the  valleys.  Not  only  this,  but  most  of  the  divides  between  the 
valleys  are  so  narrow  as  to  be  ridges  rather  than  plateaus.  Travelling  in  a 
straight  course  in  almost  any  direction,  in  most  parts  of  the  county,  one  would 
descend  from  a  ridge  over  a  steep  slope  to  a  narrow  valley,  and  ascend  on  the 
other  side  by  an  equally  steep  slope,  to  another  ridge,  which  is  followed,  in 
turn,  by  another  valley,  and  this  by  another  ridge. 

In  some  places,  the  tributary  valleys  and  ravines  dissect  the  ridges 
between  the  larger  valleys  into  hills.  There  are  few  parts  of  the  surface 
from  which  rain  water  does  not  run  promptly.  After  heavy  showers,  the 
creeks  are  swollen  promptly,  but  the  waters  subside  about  as  rapidly  as  they 
rise.  The  writer  has  seen  a  short,  insignificant  creek  rise  to  the  proportion  of 
a  raging  torrent,  and  sink  back  again  almost  to  normal  proportions,  in  four 
hours.  Most  of  the  slopes  to  the  valleys  are  convex  upward.  This  is  one 
of  the  distinctive  features  of  the  region. 

A  necessary  counterpart  of  the  topography  just  sketched  is  the  general 
absence  of  large  areas  which  approach  flatness.  Narrow  flats,  less  than  a  mile 
wide,  border  the  Ohio  near  the  southwest  and  southeast  corners  of  the  county, 
and  there  are  lesser  flats  along  the  lower  courses  of  some  of  the  larger  creeks, 
as  Honey  Creek  in  Battery  Rock  Township,  Rock  and  Harris  creeks  in  Rock 
Creek  Township,  and  Big  Creek  in  McFarlan  Township.  The  flats  along  the 
creeks,  even  at  their  lower  ends,  are  in  but  few  cases  so  much  as  half  a  mile 
wide.  Along  Hogthief  Creek  in  the  western  part  of  McFarlan  Township, 
along  Peters  Creek  in  the  northwestern ^part  of  Cave  in  Rock  Township,  and 
along  Harris  Creek  in  Rock  Creek  Township,  there  are  comparable  flats  for 
short  distances,  some  four  miles  back  from  the  main  streams.  With  these 
and  perhaps  a  few  other  exceptions,  most  of  the  streams  are  in  valleys  which 
have  no  flats,  or  flats  so  narrow  that  their  widths  are  measured  in  rods, 
rather  than  in  fractions  of  a  mile. 

THE    LIMESTONE    SINK    AREA 

Aside  from  the  valley  flats,  there  is  a  larger  area  in  the  northern  and 
eastern  parts  of  Cave  in  Rock  Township  and  in  the  extreme  southwestern 
part  of  Battery  Creek  Township,  where  the  surface  has  so  little  relief  as  to  be 


GENERAL   GEOGRAPHY  41 

in  contrast  with  its  rougher  surroundings.  The  area  is  shown  best  in  sections 
2,  3,  4,  and  5,  of  Cave  in  Eock  Township.  On  the  topographic  map,  the  area 
stands  out  because  of  the  fewness  of  its  contour  lines.  After  its  relatively 
slight  relief,  its  most  distinctive  feature  is  the  existence  of  numerous  small, 
undrained  depressions,  marked  by  depression  contours  on  the  topographic 
map  (see  "conventional  signs"  below  the  map).  These  depressions  are  well 
seen  along  the  east-west  road  about  2%  miles  north  of  the  Ohio,  and  along 
the  north-south  road  between  the  village  of  Cave  in  Eock  and  Love  School. 
More  than  40  of  these  depressions  (sinks)  are  represented  on  the  topographic 
map  as  containing  ponds,  most  of  which  are  only  a  few  rods  across.  There 
are  other  ponds  in  sinks  of  the  same  type  (1)  in  the  southwest  corner  of 
Battery  Eock  Township,  the  area  where  they  occur  being  a  continuation  of 
the  larger  area  in  Cave  in  Eock  Township;  (2)  in  McFarlan  Township  just 
northeast  of  Elizabethtown ;  and  (3)  in  Eosiclare  Township,  north  and  north- 
east of  the  village  of  Eosiclare  for  a  distance  of  about  two  miles.  In  this 
last  area  although  the  ponds  are  not  shown  on  the  map,  there  are  a  few  small 
ones  which  persist  through  all  but  the  driest  parts  of  the  year.  A  similar 
but  smaller  area  is  found  in  sees.  14,  23,  and  26  of  Eosiclare  Township. 

Unlike  the  topography  of  the  rest  of  the  county,  the  topography  of  these 
areas  was  not  produced  wholly  by  the  mechanical  erosion  of  running  water. 
All  the  areas  where  these  sinks  and  ponds  appear  are  underlain  by  the  same 
formation,  the  Fredonia  limestone.  This  limestone  would  seem  to  be  more 
soluble  than  most  of  the  other  formations  of  the  county,  and  where  the 
surface  was  flat  enough  to  allow  much  of  the  rain  water  to  enter  the  ground, 
instead  of  running  off  over  the  slopes,  the  entering  water  either  dissolved  out 
openings,  or  else  developed  underground  caves,  the  roofs  of  which  have  col- 
lapsed, making  the  sinks.  Probably  some  of  the  sinks  are  of  the  latter  type, 
and  the  steepness  of  their  slopes  suggest  that  the  collapse  was  recent;  but 
most  of  them  appear  to  be  depressions  developed  from  the  surface,  by  descend- 
ing waters.  Surface  drainage  entering  the  basins  forms  ponds  in  some  cases, 
while  in  others  it  finds  an  underground  outlet,  as  the  many  dry  sinks  show. 
This  type  of  topography,  characterized  particularly  by  undrained  sinks,  is 
known  as  karst  topography,  from  an  area  in  southwestern  Austria  where 
similar  features,  though  on  a  much  larger  scale,  are  pronounced. 

There  is  one  anomalous  minor  feature  of  the  topography,  perhaps  con- 
nected with  the  limestone  sinks  in  origin,  which  deserves  brief  mention.  The 
valley  of  Hosick  Creek,  for  example,  is  much  wider  two  miles  above  the  Ohio 
than  nearer  the  main  stream.  A  similar  condition  of  things  exists  along  Big 
Creek,  whose  valley  is  much  wider  four  miles  above  the  Ohio,  than  at  most 
points  lower  down  the  stream.  The  valley  of  the  creek  a  mile  and  a  half 
northwest  of  the  village  of  Eosiclare  is  another  illustration,  and  Harris  Creek 
in  Eock  Creek  Township  affords  still  another. 


42  GEOLOGY    OF    ITAPDIN    COUNTY 

In  all  these  cases,  the  wide  parts  of  the  valleys  are  in  limestone.  It  seems 
possible  that  these  wide  places  were  once  basins  without  outlets,  similar  to 
those  in  some  of  the  limestone  areas  now,  and  that  they  subsequently  acquired 
outlets.  If  the  broad  depression  a  mile  and  a  half  northeast  of  the  village  of 
Cave  in  Bock  were  to  acquire  an  outlet,  as  by  the  headward  development  of 
a  valley,  this  valley  would  be  wide  where  the  depression  is,  and  narrow  below. 
An  illustration  on  a  much  larger  scale  is  afforded  by  the  larger  depression  a 
mile  northwest  of  Love  School,  two  miles  north  of  the  village  of  Cave  in 
Bock.  If  the  head  of  the  drainage  line  in  the  south  part  of  section  10  were  to 
advance  a  half  mile  to  the  northward,  it  would  connect  with  this  depression. 
There  would  then  be  a  valley  wider  above  and  narrower  below.  The  wide 
valley  of  Hosick  Creek  at  Bassett  School  conceivably  may  have  originated 
in  some  such  way.     An  alternative  explanation  is  suggested  on  a  later  page. 

Topography  and  Boads 

With  the  exceptions  noted,  the  roughness  of  surface  is  so  great  as  to 
have  had  profound  influence  on  the  development  of  the  county.  The  topo- 
graphic map  shows  only  the  short  railway  in  Ohio  Valley  very  recently  con- 
structed to  serve  the  fluorspar  mines  in  the  vicinity  of  Bosiclare.  The 
existence  of  only  one  and  that  but  a  local  railroad  is  accounted  for  by 
the  roughness  of  the  surface.  Not  only  is  the  uneveness  of  the  surface 
an  obstacle  to  their  construction,  but  it  is  so  great  as  to  diminish 
the  volume  of  produce  from  the  land  which  might  otherwise  call  for  ship- 
ment. The  presence  of  a  navigable  stream  on  the  east  and  south  borders  of 
the  county  makes  the  absence  of  railways  less  serious  than  it  would  be 
otherwise. 

The  topographic  map  shows  also  that  there  are  few  roads  in  the  county 
which  are  straight  for  any  considerable  distance,  and  some  of  those  which  are 
straight  are  over  such  rough  country  as  to  make  them  hard  to  travel.  The 
east-west  road  a  mile  and  a  half  north  of  the  Ohio  in  Cave  in  Bock  Township 
is  an  example.  Most  of  the  roads  properly  follow  winding  valleys  or  the 
divides  between  them,  their  courses  being  controlled  by  topography. 

But  few  of  the  roads  of  the  county  have  been  put  into  first  class  con- 
dition. In  many  places  there  are  no  bridges  at  the  crossing  of  creeks,  and 
after  heavy  rains  the  streams  are  too  deep  and  swift  to  be  forded.  This  makes 
travel  over  some  roads  impossible  for  short  periods  of  time.  Furthermore  the 
short  floods  sometimes  so  wash  the  stream  beds  as  to  make  crossing  difficult 
after  the  flood  goes  clown.  In  not  a  few  places,  roads  follow  the  beds  of  small 
creeks,  and  such  roads  are  impassable  many  times  a  year.  In  other  places, 
dirt  roads,  which  are  reasonably  good  in  dry  weather,  become  very  heavy 
when  the  ground  is  wet.  Fully  half  the  roads  shown  on  the  topographic  map 
are  difficult  at  all  times,  either  because  of  the  steepness  of  their  grades,  or 


GENERAL    GEOGRAPHY  43 

their  stoniness,  or  both.  Most  of  the  roads  represented  by  broken  lines  on 
the  map,  and  many  others,  belong  in  this  category.  It  follows  that  getting 
crops  to  market  is  both  difficult  and  expensive. 

Topography  and  Farming 

Most  of  the  surface  of  the  county  is  too  rough  for  good  farming.  Some- 
thing like  a  third  of  the  area  never  was  cleared  of  timber,  and  a  large  fraction 
of  that  which  once  was  cleared  and  farmed  is  tilled  no  longer.  The  total 
area  actually  under  cultivation  probably  is  not  half  of  the  total  acreage  of 
the  county. 

Xot  only  has  the  steepness  of  the  slopes  made  cultivation  difficult,  but  it 
has  favored  the  washing  away  of  the  soil.  Xot  very  fertile  at  the  outset,  the 
soil  has  been  impoverished  by  the  removal  of  is  upper  part  by  surface  wash 
since  the  timber  was  cut,  and  this  upper  part  was  the  most  valuable  part, 
since  it  contained  most  of  the  organic  matter  needed  for  the  vigorous  growth 
of  plants.  Xot  only  has  much  of  the  surface  part  of  the  soil  been  washed 
away,  but  in  places  the  slopes  have  been  gullied  so  deeply  that  tillage  is  now 
impossible.  While  this  is  not  true  of  a  large  proportion  of  the  surface,  it  is 
true  of  local  slopes  in  scores,  and  probably  in  hundreds,  of  places.  It  is  not 
altogether  clear  whether  cultivation  of  the  gullied  slopes  was  given  up  because 
of  the  gullies,  or  whether  their  development  followed  the  abandonment  of  the 
land.  The  latter  probably  is  the  fact  to  a  large  extent,  for  many  lands  cleared 
but  not  now  tilled,  are  not  gullied,  showing  that  gullying  was  not  the  cause  of 
their  abandonment. 

Many  of  the  slopes  which  have  been  cleared  should  have  been  left  in 
forest.  The  larger  timber  might  have  been  cut,  properly  enough,  but  the 
small  trees  should  have  been  allowed  to  grow.  The  slopes  once  cleared  but 
no  longer  tilled,  should  be  re-forested  as  promptly  as  possible.  If  trees  had 
been  planted  when  tillage  ceased,  re-forestation  would  be  well  under  way 
already,  and  the  value  of  the  land  would  be  much  greater  than  it  now  is,  for 
not  only  would  the  trees  themselves  be  valuable  some  day,  but  they  would 
help  to  prevent  the  washing  away  of  the  soil,  and  help  to  restore  its  depleted 
content  of  organic  matter. 

A  slope  of  1  in  10,  which  means  a  slope  of  528  feet  per  mile,  or  a  little 
more  than  oy20,  may,  in  general,  be  tilled  with  safety,  if  care  is  taken  to 
prevent  erosion  by  rain  wash.  In  many  situations,  and  with  types  of  soil 
which  do  not  wash  readily,  slopes  of  1  in  8,  660  feet  per  mile,  or  a  little  more 
than  7°,  may  be  tilled  safely,  with  proper  care.  Steeper  slopes  rarely  are 
tilled  profitably  for  any  considerable  period  of  time  by  the  methods  in  use  in 
this  region.  But  many  of  the  cleared  slopes  of  the  region  are  considerably 
steeper,  in  not  a  few  cases  800  feet  to  the  mile,  and  in  some  as  much  as  1000 
feet  (nearly  11°).     For  the  future  ,2'ood  of  the  county,  it  would  be  well  if  all 


44  GEOLOGY    OF    HARDIN    COUNTY 

cleared  lands  having  slopes  of  more  than  600  feet  per  mile  were  re-forested. 
Care  should  be  taken  in  re-foresting  to  secure  varieties  of  trees  which  will 
grow  well  in  the  climate  and  soil  of  the  region.  To  this  end  the  advice  of  an 
expert  forester  should  be  sought.  If  this  is  not  practicable,  it  is  safe  to  plant 
hardy  native  types  of  good  timber  trees.  The  black  locust  has  been  found 
to  be  a  good  tree  for  re-foresting.1  It  is  recommended  partly  because  it 
flourishes  in  soils  which  are  poor  in  nitrogenous  compounds,  as  most  of  the 
soils  of  this  county  are,  and  partly  because  it  makes  good  post  and  tie  timber, 
for  which  there  is  ready  market. 

Mantle  Rock 
soil 

Hardin  County  is  south  of  the  limit  of.  glaciation,  though  its  northwest 
coiner  is  less  than  ten  miles  from  the  southern  border  of  glacial  drift.  Though 
there  is  no  glacial  drift  in  the  county,  the  soil  was  not  derived  wholly  from 
the  decay  of  the  underlying  rock.  Over  most  of  the  surface  except  where 
slopes  are  very  steep,  there  is  a  mantle  of  clayey  loam,  overlying  earthy  matter 
which  shows  by  its  composition  that  it  was  derived  from  the  rock  beneath  by 
processes  of  decay.  The  surface  loam  is  absent  only  on  steep  slopes  and  valley 
fiats.  Thicknesses  of  four  to  six  feet  are  common,  and  thicknesses  twice  as 
great  are  not  rare.  The  loam  is  conspicuously  thick  on  gentle  slopes  at  the 
bases  of  steeper  ones,  as  in  the  northern  part  of  Cave  in  Rock  Township. 
This  obviously  suggests  that  in  such  situations  it  has  been  washed  down  from 
the  steeper  surfaces  above  and  lodged  on  the  flats  or  low  slopes  below ;  but  no 
such  explanation  is  applicable  to  the  loam  on  the  ridges,  where  it  is  as  distinct 
as  elsewhere. 

The  surface  loam  is  unlike  the  obviously  rock-derived  earth  beneath,  in 
that  it  contains  no  fragments  of  the  underlying  rock.  In  many  places  the  two 
types  of  material  differ  in  color,  as  well  as  composition.  This  is  especially 
true  where  the  underlying  rock  is  limestone.  The  earthy  matter  to  which  the 
decay  of  this  rock  gives  rise  is  dark,  reddish-brown  clay,  and  contains  bits  of 
residual  chert  which  originally  were  in  the  limestone.  The  loam  above  is 
much  lighter  in  color,  is  less  compact,  and  contains  no  chert  or  other  rock  frag- 
ments. Where  the  underlying  rock  is  sandstone,  the  difference  in  color 
between  the  surface  loam  and  the  residual  earth  below  is  less  conspicuous,  but 
the  underlying  material  derived  from  the  sandstone  is  more  sandy  than  the 
loam  above.  As  a  rule,  however,  the  upper  loam  is  more  sandy  where  the 
underlying  rock  is  sandstone  than  where  it  is  limestone.  This  suggests  that 
the  character  of  the  upper  loam  is  influenced,  to  some  extent,  by  the  character 
of  the  underlying  rock. 


1  Hopkins,    Cyril    G.,    and    others,    Hardin    County    soils:       Agr.    Exp.     Station    Soil 
Report  No.   3,   1912. 


GENERAL   GEOGRAPHY  45 

It  seems  probable  that  the  loam  is  made  up  (1)  partly  of  the  products 
of  rock  decay,  modified  near  the  surface  by  the  various  processes  of  weather- 
ing, and  especially  by  the  action  of  insects,  earthworms,  and  other  burrowing 
animals  which  bring  up  the  fine  material,  leaving  the  coarse  below,  and  (2) 
partly  of  dust  which  has  been  blown  about  within  the  region,  and  blown  in 
from  other  areas.  The  surface  portion  has  been  affected  much  more  than  the 
deeper  earths  by  all  processes  of  weathering,  such  as  solution  and  freezing 
and  thawing,  and  by  the  action  of  roots,  insects,  earthworms  and  burrowing 
animals  of  all  sorts. 

This  surface  loam  sometimes  has  been  called  loess,1  though  but  little  of 
it  has  the  texture  characteristic  of  loess,  and  none  of  it  has  been  observed  to 
have  the  other  distinctive  features  of  loess,  such  as  fossil  land-snail  shells, 
and  concretions  of  calcium  carbonate.  The  characteristic  marks  of  loess  may 
be  present  here  and  there,  but  they  are  rare,  if  present  at  all.  Nor  is  the 
loam  commonly  calcareous,  as  most  loess  is,  and  it  has  not  the  physical 
characteristics  which  permit  it  to  stand  in  the  steep  faces  so  characteristic  of 
typical  loess.  If  loess  is  defined  on  the  basis  of  textural  features  and  com- 
position, most  of  the  surface  loam  of  this  county  is  not  loess.  If  loess  is 
defined  as  wind-deposited  dust,  some  part  of  the  Hardin  County  loam  might 
qualify;  but  the  wind-deposited  earths  probably  are  so  mingled  with  those 
derived  from  the  rock  beneath,  as  to  make  the  name  loess  of  doubtful 
propriety. 

The  soil  report  of  Hardin  County  just  cited  indicates  that  the  soil  of 
nearly  90%  of  the  area  of  the  county  is  "upland  timber"  soil,  of  which  70.56% 
is  classed  as  "yellow  silt  loam."  The  same  report  gives  to  the  county  10.5% 
of  "swamp  and  bottom"  land,  and  more  than  1%  of  "terrace"  soil. 

The  upland  soils,  especially,  are  notably  deficient  in  nitrogen,  a  short- 
coming that  can  be  overcome  best2  by  the  growth  of  clover,  alfalfa,  cowpeas, 
and  soybeans,  the  crop  being  turned  under  as  "green  manure."  In  order  to 
get  these  crops  to  grow  well,  it  is  important  in  most  parts  of  the  county  to 
add  limestone  to  the  soil.  Since  limestone  is  abundant  in  the  county  and 
quarries  could  be  opened  at  numerous  points,  it  should  not  be  difficult  to 
supply  the  soil  with  the  crushed  limestone  favoring  the  growth  of  the  above 
crops,  which,  turned  under,  would  greatly  increase  productivity. 

In  view  of  the  topography  of  the  county,  and  the  resulting  lack  of  rail- 
roads and  good  wagon  roads,  it  would  seem  that  more  attention  should  be 
given  to  stock-raising,  partly  because  stock  can  be  marketed  more  readily  than 
grain,  and  partly  because  stock-raising  would  do  much  to  make  the  soil  more 
productive.  In  this  event,  the  crops  raised  for  harvest  should  be  those  which 
will  serve  as  winter  feed  for  the  stock.     In  farther  support  of  the  above  sug- 

1  Hopkins,  Cyril  G.,  and  others,  Hardin  County  soils  :     Agr.  Exp.  Station  Soil  Report 
No.   3,   1912. 

2  Op.  cit. 


46  GEOLOGY    OF    HARDIN    COUNTY 

gestion,  it  may  be  noted  that  though  much  of  the  cleared  land  has  slopes  too 
steep  for  continuous  cultivation,  it  might  well  be  used  for  pasture.  Pasture 
land  does  not  wash  as  readily  as  land  which  is  tilled.  Even  the  timber  lands 
are  serviceable  to  a  considerable  extent  for  pasture.  Few  sheep  are  now  raised 
in  the  county,  although  the  region  would  seem  to  be  well  adapted  to  them. 

There  are  some  lands  which  probably  are  well  adapted  to  fruit  raising, 
and  this  might  well  receive  more  attention  than  it  has.  Little  fruit  is  at 
present  raised.  If  undertaken  on  any  considerable  scale,  attempted  fruit 
culture  should  be  under  the  advice  of  someone  familiar  with  the  soil- 
requirements  of  different  fruits,  and  with  the  soils  and  topography  of  this 
region. 

In  valleys  where  there  are  alluvial  flats,  the  soils  of  the  fiats  are  made  up 
of  detritus  washed  from  the  adjacent  hills  and  ridges.  They  are  composed 
largely  of  the  surface  soils  once  on  the  uplands,  washed  down  to  the  valleys 
below.  Such  soils  contain  more  organic  matter  than  the  upland  soils,  because 
the  part  of  the  upland  soils  containing  most  organic  matter  is  the  part  which 
was  washed  down  and  deposited  on  the  flats.  These  alluvial  soils  are  fertile, 
and  when  properly  tilled,  yield  good  crops, — on  the  average  the  best  in  the 
county.  But  the  total  area  of  bottom  land  is  small  (about  10.5%),  and  some 
of  the  valley  flats  are  so  narrow  as  not  to  invite  cultivation. 

At  a  few  places  there  are  low  terraces  along  the  valleys.  These  are  best 
developed  along  the  Ohio,  as  in  the  vicinity  of  Eosiclare  and  farther  west,  and 
along  the  lower  ends  of  its  tributaries.  In  a  rather  recent  stage  of  geological 
history  (the  glacial  period),  the  valley  of  the  Ohio  was  rilled  up  somewhat 
with  alluvial  material,  and  this  filling  of  the  main  valley  dammed  up  its 
tributaries,  and  slack  water  deposits  were  made  in  them.  The  deposits  made 
at  this  time  in  the  creek  valleys  are  unlike  other  parts  of  the  mantle  rock  in 
the  county  in  that  they  are  highly  calcareous,  and  in  some  cases  are  now  full 
of  calcareous  concretions.  A  good  illustration  may  be  seen  where  the  road 
crosses  the  lower  end  of  the  valley  in  the  southwest  corner  of  sec.  22,  Cave  in 
Eock  Township. 

In  a  few  places  there  is  a  little  eolian  (wind  blown)  sand  along  the 
Ohio  valley,  as  in  sec.  33,  northeast  of  Eosiclare,  and  in  sec.  33,  Cave  in  Eock 
Township.  Nowhere  was  such  sand  seen  to  make  considerable  dunes.  In 
association  with  it,  fairly  typical  loess  in  small  quantities  was  seen  at  two 
or  three  points,  as  at  the  locality  in  Cave  in  Eock  Township  just  mentioned. 
The  sand  here  overlies  the  loess. 

Eock  Cliffs 

Eock  cliffs  are  singularly  few  considering  the  roughness  of  the  surface. 
They  exist  at  some  points  along  Ohio  Eiver,  and  at  a  few  other  points  in  each 
township.     They  are  mostly  at  localities  where  the  topographic  map  shows 


GENERAL   GEOGRAPHY  47 

closely  crowded  contours,  as  on  the  south  face  of  Buzzards  Point  in  the 
northern  part  of  Monroe  Township.  Considering  the  steepness  of  the  slopes, 
it  is  rather  remarkable  that  the  solid  rock  is  so  generally  concealed  by  mantle 
rock.  This  would  hardly  be  the  case  if  the  mantle  rock  were  largely  a  product 
of  rock  decay. 

History  oe  the  Topography 

Eocks  of  diverse  sorts,  including  sandstones,  shales,  and  limestones, 
underlie  the  county,  and  appear  at  the  surface  in  diverse  places,  especially 
on  steep  slopes;  but  they  appear  also  in  other  places,  as  in  the  bottoms  of 
many  of  the  small  valleys.  These  rock  formations  are  of  different  degrees 
of  hardness,  and  as  a  consequence  have  been  eroded  unequally.  Most  of  the 
conspicuous  elevations  are  of  resistant  sandstone,  while  much  of  the  lower 
land  is  underlain  by  less  resistant  shale  and  limestone. 

The  rock  strata  are  nearly  horizontal  in  most  places.  So  generally  is 
this  true,  that .  conspicuous  ridges  are  nowhere  formed  by  the  outcropping 
edges  of  uptilted  resistant  beds.  The  strata  of  limestone,  shale,  and  sand- 
stone, originally  formed  beneath  the  sea  as  the  marine  fossils  in  them  show, 
were,  at  some  later  time,  pushed  up  above  their  surroundings,  and  the  present 
topography  is  the  result  of  the  erosion  of  running  water  on  this  uplifted  mass; 
but  the  history  of  the  topography  probably  is  less  simple  than  this  brief 
statement  implies. 

From  this  county  and  its  surroundings,  it  is  inferred  that  there  was 
once  a  sub-even  surface  in  the  region,  the  remnants  of  which  now  have  an 
elevation  of  about  900  feet.  The  existing  remnants  of  this  surface,  if  this 
conclusion  is  correct,  are  seen  at  Buzzards  Point  at  the  north  edge  of  Monroe 
Township  3  miles  east  of  its  western  border;  a  mile  and  a  half  west  of 
Buzzards  Point  in  sec.  1 ;  at  High  Knob  just  north  of  the  county  line  north 
of  the  village  of  Karbers  Eidge;  as  well  as  at  more  distant  points  outside  the 
county.  In  the  southwest  corner  of  the  county,  the  conspicuous  Melcher  Hills 
probably  is  a  remnant  of  the  Buzzards  Point  plain,  though  lowered  considerably 
below  its  level.  This  old  plain,  whose  remnants  are  so  meager  that  the  plain 
itself  is  somewhat  hypothetical,  may  be  called  the  Buzzards  Point  plain- 
When  it  was  in  existence  as  a  continuous  plain  over  the  whole  region,  it  did 
not  have  an  elevation  of  900  feet.  Probably  it  was  then  several  hundred  feet 
(500  to  600)  lower  than  its  existing  remnants.  From  the  topography  of 
this  county  alone,  it  would  not  be  clear  whether  this  Buzzards  Point  plain,  the 
highest  represented  in  the  region  and  the  starting  point  for  the  decipherable 
physiographic  history  of  the  county,  was  the  surface  of  the  land  as  it  was 
pushed  up  out  of  the  sea,  or  whether  it  was  a  plain  developed  from  an  older 
surface  by  the  prolonged  erosion  of  running  water.  The  distribution  and  the 
relations   of  the   underlying   rock   strata,   however,   make   it   clear  that   con- 


48  GEOLOGY   OF    HAEDIN    COUNTY 

siderable  thicknesses  of  rock  had  been  removed  from  the  region  before  the- 
Buzzards  Point  plain  was  developed. 

The  date  of  the  existence  of  this  old  plain  is  not  fixed,  even  in  geologic 
terms.  If  certain  analogies  in  other  regions  may  be  trusted,  it  may  have  been 
in  existence  at  the  close  of  the  Mesozoic  Era;  but  this  is  at  present  nothing 
more  than  conjecture.  After  its  development,  the  region  was  elevated,  rela- 
tive to  its  surroundings.  With  increase  in  its  elevation,  its  streams  were 
quickened,  erosion  became  vigorous,  and  valleys  were  developed  in  the  plain, 
notably  roughening  its  surface. 

There  are  strong  suggestions  that  the  uplift  of  the  region  to  its  present 
height  took  place  by  successive  stages,  separated  by  considerable  intervals  of 
time.  Eemembering  that  the  succession  of  uplifts  of  the  old  sea  bottom 
which  preceded  the  development  of  the  Buzzards  Point  plain  is  unknown, 
succeeding  events  may  be  sketched.  If  these  events  are  sketched  in  affirmative 
terms,  it  is  for  the  sake  of  simplicity,  rather  than  because  the  record  is  so 
clear  as  to  make  the  succession  of  events  unequivocal. 

FIRST    UPLIFT 

If  the  Buzzards  Point  plain,  now  860  to  900  feet  above  the  sea,  was  300 
feet  above  the  sea  when  the  development  of  present  topography  began,  there 
is  some  suggestion  that  its  first  elevation  was  250  to  300  feet.  In  this  uplifted 
surface,  the  quickened  streams  cut  valleys  to  depths  corresponding  roughly 
to  the  amount  of  uplift.  After  the  valleys  cut  in  the  uplifted  plain  reached 
some  such  depth  as  250  to  300  feet,  the  streams  developed  flats  in  their  bot- 
toms after  the  manner  of  all  normal  streams.  These  flats  appear  to  have 
become  extensive  and  the  divide  between  them  low,  so  that  much  of  the  area 
of  the  county  was  brought  down  nearly  to  their  level.  The  result  was  an 
imperfectly  developed  peneplain  250  to  300  feet  below  the  level  of  the 
Buzzards  Point  plain. 

The  peneplain  of  this  stage  has  been  much  dissected  by  later  erosion,  but 
remnants  of  it  are  seen  in  the  crests  of  many  hills  and  ridges  which  have  a 
nearly  common  elevation,  600  to  640  feet  above  the  sea.  Among  such- 
remnants  in  Monroe  Township  may  be  mentioned  the  ridge  on  which  the 
village  of  Karbers  Eidge  is  located.  Since  this  sub-even-crested  ridge  and  its 
northeastward  extension  in  sections  10  and  3  to  the  east  of  the  village,  and 
similar  crests  in  the  immediate  vicinity  to  the  south  in  sections  7,  8,  9,  16, 
and  17,  are  among  the  most  extensive  remnants  of  this  plain,  if  the  interpre- 
tation here  given  is  correct,  it  may  be  called  the  Karbers  Ridge  plain.  There 
are  crests  at  about  the  same  level  in  the  eastern  part  of  the  same  township,  as 
at  Philadelphia  School,  at  several  points  in  sees.  13,  14,  15,  22,  23,  24,  25,  and 
26,  and  crests  in  the  western  part  in  the  vicinity  of  Hicks,  in  sees.  19,  24,  25, 
29,  30,  31,  and  32.     In  these  sections  many  hills  and  ridge  tops  come  to  a 


GENERAL   GEOGRAPHY 


49 


nearly  common  level,  and  many  others  which  are  only  a  little  higher.  In 
Rock  Creek  Township  similar  crests,  similarly  interpreted,  are  in  sees.  5,  6, 
7,  9,  10,  19,  20,  21,  22,  24,  25,  26,  30,  and  35,  and  many  others  but  a  little 
higher.  In  Battery  Eock  Township  there  are  crests  correlated  with  the  fore- 
going in  sees.  19,  20,  29,  31,  and  farther  south  in  sees.  5,  7,  8,  and  9.  Crests 
correlated  with  the  above  find  little  representation  in  the  other  townships, 
though  in  Cave  in  Rock  Township  areas  in  sees.  1  and  6  may  be  mentioned, 
and  in  McFarlan  Township,  in  sec.  17. 

Quite  as  significant  as  the  fact  that  so  many  crests  come  to  accordant 
levels,  is  the  fact  that  these  crests  are  underlain  by  diverse  rock  formations 
of  different  degrees  of  resistance.  This  fact  gives  support  to  the  view  that 
the  hypothetical  Karbers  Ridge  plain  was  once  a  fact,  for  once  a  region  under- 
lain by  rock  of  diverse  resistance  is  roughened  by  erosion,  it  does  not  again 
approach  planeness  until  it  is  reduced  nearly  to  the  level  of  the  flats  of  the 
rivers  which  drain  it. 

It  is  to  be  noted  that  most  of  the  remnants  of  the  Karbers  Ridge  plain 
are  well  back  from  the  Ohio,  where  in  later  cycles  of  erosion,  the  surface 
should  have  suffered  least. 

The  fact  and  the  process  of  development  of  flats  along  streams  is  illus- 
trated along  Ohio  and  Saline  rivers  now.  Both  these  streams  have  flats  of 
considerable  width.  Their  tributaries  have  narrow  flats,  especially  at  their 
lower  ends,  and  most  of  them  none  at  all  a  few  miles  above  their  mouths. 
All  these  flats  are  being  widened  all  the  time.  Humanly  speaking,  the  pro- 
cess is  extremely  slow,  but  in  time  the  flats  would  be  so  widened,  always  at 
the  expense  of  the  ridges  between  them,  that  they  would  occupy  the  larger 
part  of  the  surface.  This  is  what  is  conceived  to  have  taken  place  after  the 
first  uplift,  while  the  Karbers  Ridge  plain  was  developing. 

Although  much  of  the  surface  of  the  county  was  perhaps  reduced  250 
feet  or  so,  there  remained  above  this  lower  surface,  some  unreduced  remnants 
of  the  preceding  higher  Buzzards  Point  plain.  The  highest  point  in  the 
Melcher  Hills  in  the  southwest  corner  of  the  county  is  somewhat  above  the 
level  of  the  Karbers  Ridge  plain,  and  is  probably  a  lowered  remnant  of 
the  Buzzards  Point  plain,  lowered  somewhat  in  later  time. 


SECOND   UPLIFT 


After  considerable  portions  of  the  area  of  the  county  had  been  reduced  to 
the  Karbers  Ridge  peneplain,  now  represented  by  hill  and  ridge  tops  600 
to  640  feet  above  the  sea,  another  uplift  of  100  to  120  feet  appears  to  have 
taken  place.  This  uplift  terminated  the  incomplete  cycle  of  erosion  just 
sketched.  The  streams,  quickened  by  the  new  uplift,  deepened  their  valleys 
in  keeping  with  the  new  position  of  the  surface.    After  having  deepened  their 


-4  G 


50  GEOLOGY  OF  HARDIN  COUNTY 

valleys  to  grade.,  the  streams  developed  new  flats  in  their  bottoms  100  to  120 
feet  below  the  level  at  which  flats  were  developed  in  the  preceding  cycle,  at 
a  level  which  is  now  500  to  5-10  feet  above  the  sea,  though  then  much  lower. 
In  any  valley  tributary  to  the  Ohio  the  flat  developed  first  at  its  lower  end, 
and  was  extended  slowly  up  stream  at  the  same  time  that  it  was  being  widened. 
The  valley  fiats  therefore  became  wider  along  main  streams  and  at  the  lower 
ends  of  their  tributaries,  and  remained  narrower  farther  up  these  streams. 
While  the  flats  developed  at  this  time  appear  to  have  become  wide  in  the 
lower  parts  of  the  valleys  of  the  tributary  creeks,  they  do  not  appear  to  have 
been  wide  in  their  middle  courses,  and  do  not  seem  to  have  appeared  at  all 
at  their  upper  ends,  when  this  very  incomplete  cycle  of  erosion  was  interrupted 
by  another  uplift. 

The  most  extensive  remnants  of  this  plain  are  not  so  far  from  the  Ohio 
as  the  remnants  of  the  Karbers  Ridge  plain.  Illustrations  are  seen  in  the 
crests  of  hills  and  ridges  which  have  an  elevation  of  about  520  feet  in  sees. 
1,  6,  7,  9,  10,  11,  13,  15,  16,  and  181,  in  McFarlan  Township;  in  sees.  1,  11, 
12,  13,  14,  23,  25,  26,  and  35,  Eosiclare  Township;  in  sees.  7  and  17,  Cave  in 
Rock  Township;  in  sees.  4,  9,  and  10  in  the  southern  part  of  Battery  Rock 
Township,  and  in  sees.  18,  28,  31,  and  33  in  the  northern  part;  in  sees.  2,  3 
(near  Saline  River  valley),  23,  and  25,  Rock  Creek  Township;  and  at  a  num- 
ber of  points  in  the  southwest  part  of  Monroe  Township,  especially  in  sees. 
35  and  36. 

No  point  mentioned  which  shows  distinct  remnants  of  this  plain,  has  a 
name.  If  the  area  in  the  south  part  of  sec.  10  and  the  north  part  of  sec.  15, 
McFarlan  Township,  had  a  name,  it  would  be  given  to  this  partial  plain  which 
came  to  distinct  development  only  within  a  few  miles  of  main  streams.  For 
want  of  a  better  name,  it  will  be  called  the  McFarlan  plain.  Above  it,  even 
within  three  or  four  miles  of  the  Ohio,  rose  remnants  of  the  Karbers  Ridge 
plain,  while  farther  from  the  Ohio  such  remnants  were  extensive.  The  Mc- 
Farlan plain  therefore  was  much  less  extensive  and  much  less  well  developed 
than  the  Karbers  Ridge  plain. 

As  in  the  case  of  the  Karbers  Ridge  plain,  the  remnants  of  the  McFarlan 
plain  are  underlain  by  rocks  of  different  sorts,  and  of  different  degrees  of 
resistance. 

THIRD    UPLIFT 

After  the  valley  flats  of  the  .McFarlan  cycle  had  reached  considerable 
development,  with  small  remnants  of  the  Buzzards  Point  plain,  and  much 
larger  remnants  of  the  Karbers  Ridge  plain,  above  them,  the  region  underwent 
a  third  upraising,  100  to  120  feet  in  amount,  and  the  process  of  valley  deepen- 
ing was  repeated.  After  being  deepened  by  an  amount  roughly  equal  to  the 
uplift,  the  streams  in  these  deepened  valleys  began  to  develop  flats  at  a  level 


GENERAL   GEOGRAPHY  51 

which  is  now  some  400  feet  above  the  sea,  and  100  to  120  feet  below  the  Mc- 
Farlan  plain.  The  flats  developed  at  this  time  appear  to  have  become  somewhat 
wide  along  main  streams  and  the  lower  ends  of  the  larger  tributaries,  but  to 
have  had  little  development  in  the  upper  reaches  of  the  creeks. 

Remnants  of  the  plains  developed  at  this  stage  are  chiefly  seen  in  Rosi- 
clare,  McFarlan  and  Cave  in  Rock  townships.  Near  the  Ohio  they  are  the 
low  upland  crests,  80  to  100  feet  or  so  above  the  flood  plain  of  the  Ohio. 
Illustrations  are  found  northeast  of  Elizabethtown  for  a  mile  or  more,  between 
Elizabethtown  and  Rosiclare,  north  of  the  latter  village,  and  in  the  vicinity  of 
the  village  of  Cave  in  Rock.  This  plain,  but  slightly  developed  except  in  the 
vicinity  of  the  Ohio,  may  be  called  the  Elizabethtown  plain,  after  the  area 
which  extends  northeast  from  that  village.  The  wide  flatfish  area  in  the 
northern  part  of  Cave  in  Rock  Township  previously  described  under  the 
heading  "The  limestone  sinks  area"  probably  dates  from  this  time.  The  con- 
siderable width  of  this  area  probably  is  connected  with  the  non-resistant  nature 
of  the  limestone  underlying  this  region. 

Back  from  the  Ohio,  the  Elizabethtown  plain  (400  to  420  feet)  is  repre- 
sented by  flatfish  areas  along  drainage  lines,  rather  than  by  crests.  The 
flatfish  tract  a  mile  northwest  of  Elizabethtown  is  an  illustration  of  the  type 
of  which  there  are  many. 

FOURTH   UPLIFT 

Again  elevation  ensued,  amounting  to  perhaps  80  feet,  and  again  the 
streams  set  about  the  task  of  reducing  their  valleys  to  levels  in  keeping  with 
the  new  stand  of  the  land.  Since  this  uplift,  the  Ohio  has  developed  a  narrow 
flat  at  an  elevation  above  sea  level,  ranging  from  about  340  feet  at  the  north- 
eastern corner  of  the  county,  to  about  320  feet  at  the  southwestern  corner, 
and  the  tributary  streams  have  developed  flats  near  their  lower  ends  in 
harmony  with  the  flat  of  the  Ohio.  The  flats  along  the  tributaries,  however, 
have  not  been  extended  far  up  the  valleys,  so  that  in  the  upper  reaches  of 
most  of  the  streams,  the  deepening  of  the  valleys  since  the  last  uplift,  has 
been  but  a  continuation  of  the  deepening  which  was  in  progress  before.  In 
other  words,  the  last  uplift  shows  itself  in  the  character  of  the  topography 
near  the  main  streams,  but  not  elsewhere. 

The  fact  that  several  of  the  creeks  have  better  developed  flats  some  miles 
above  their  mouths,  than  near  them,  has  been  mentioned  already  under  the 
discussion  of  limestone  sinks.  In  some  cases,  these  flats  appear  to  be  the 
flats  of  the  preceding  cycle.  The  deepening  of  the  valleys  since  the  last  uplift 
has  not  yet  made  itself  felt  back  far  enough  to  destroy  the  flats  developed  in 
the  preceding  cycle.  If  all  the  flats  some  miles  above  the  lower  ends  of  the 
creeks,  and  distinctly  above  the  flat  of  the  Ohio  corresponded  to  the  level  of 
the  Elizabethtown  plain,  this  explanation  would  seem  altogether  satisfactory; 


52  GEOLOGY    OF    HARDIN    COUNTY 

but  a  number  of  them  are  at  levels  intermediate  between  the  Elizabethtown 
plain  level,  and  the  level  of  the  Ohio  valley,  and  the  above  suggestion  as  to 
their  origin  does  not  fit  these  cases. 

The  history  sketched  above  is  less  decisively  marked  than  could  be  desired. 
If  the  periods  of  erosion  after  the  second  and  third  uplifts  had  been  longer 
before  being  interrupted  by  renewed  uplift,  the  case  would  have  been  clearer. 
As  it  is,  the  areas  representing  the  several  plains,  especially  the  later  ones, 
are  less  extensive  than  could  be  wished  to  make  the  above  conclusions  certain; 
but  they  are  sufficient  to  suggest  the  inferences  drawn. 


PART  II 
STRUCTURAL  GEOLOGY 

By  Stuart  Weller  and  Chas.  Butts 


CIIAPTEK  IV— STEUCTUBAL  GEOLOGY 


Faulting 


Hardin  County,  Illinois,  is  situated  upon  the  margin  of  a  district  struc- 
turally unique  for  the  eastern  United  States.  The  unique  feature  of  this 
district  is  the  great  number  of  faults  which  crisscross  the  country,  and  break 
the  outer  crust  of  strata  into  blocks  and  fragments  of  greatly  varying  size, 
and  of  generally  rectangular,  rhombohedral,  or  triangular  surface  forms. 
The  district  so  broken  up  extends  over  parts  of  Hardin,  Pope,  and  Johnson 
counties,  Illinois,  and  Livingston,  Crittenden,  and  Caldwell  counties,  Ken- 
tucky, where,  so  far  as  known,  the  faults  are  even  more  numerous.  These 
counties,  however,  probably  comprise  only  that  part  of  the  faulted  district  in 
which  the  forces  of  the  deformational  stresses  which  produced  the  faulting 
acted  with  greatest  intensity.  The  region  to  the  south  and  southwest  is 
known  to  have  some  faults,  and  it  is  not  improbable  that  the  faulted  area 
extends  southwestwarcl  underneath  the  cover  of  more  recent  deposits  to 
western  Tennessee.  The  New  Madrid  earthquake  in  1811  and  the  formation 
of  Eeelfoot  Lake  in  western  Tennessee  possibly  were  caused  by  crustal  move- 
ments along  a  fault  belonging  to  this  general  region  of  disturbance.  Faults 
occur  as  far  east,  too,  as  Hopkinsville,  Kentucky,  and  beyond,  which  shows 
that  region  also  to  be  within  the  faulted  district.  The  Wells  Creek  basin 
with  associated  faults  of  northwestern  Tennessee  probably  lies  within  the 
general  area  of  disturbance. 

The  remarkable  fact  about  this  region  is,  that  it  is  located  in  the  midst 
of  a  great  region  of  rocks  which  are  comparatively  little  disturbed  from  their 
originally  horizontal  attitude  and  are  almost  free  from  faults.  Yet  in  the 
very  heart  of  this  vast  region  of  almost  undisturbed  rocks,  lies  this  shattered 
district  in  extreme  contrast  to  the  surrounding  regions.  There  are  but  few 
such  occurrences  in  the  world. 

Xot  less  extraordinary  is  the  common  presence  within  the  region,  of 
igneous  rocks  in  the  form  of  dikes,  sills,  and  plugs,  as  will  be  described  later. 
While  such  intrusive  occurrences  of  peridotite  are  known  in  other  undisturbed 
areas,  they  are  very  rare  and  are  not  to  be  compared  in  number  with  those  of 
this  region.  These  faults  and  igneous  intrusions  are  of  further  great  interest, 
owing  to  their  close  association  with  the  important  fluorspar  deposits  of 
Hardin  County  and  the  western  counties  of  Kentucky.     Probably  all  of  these 

55 


56 


GEOLOGY  OF  HARDIN  COUNTY 


features  of  the  county  are  traceable  to  a  common  origin,  and  consequently 
are  intimately  related  to  one  another. 

As  may  be  inferred  from  the  foregoing  statement,  a  full  discussion  of 
the  structural  geology  of  Hardin  County  involves  the  consideration  of  a 
somewhat  larger  area,  extending  westward  into  Pope  and  Johnson  counties, 
Illinois,  and  southward  into  Kentucky.  In  general  the  strike  of  the  rock 
formations  in  Hardin  County,  as  indicated  by  the  position  of  the  boundary 
between  the  Pottsville  sandstone  and  the  top  of  the  Chester  group,  extends, 
except  as  it  is  interrupted  by  faulting,  from  the  southeastern  portion  of  the 
county  towards  the  northwestern  corner,  having  a  northwesterly  course. 
About  three  miles  east  of  the  Hardin-Pope  county  boundary,  however,  the 
strike  begins  to  curve  to  the  south,  assuming  a  southwesterly  direction,  and 
where  these  formations  are  traced  into  eastern  Pope  County  the  southerly 
direction  of  the  strike  is  more  pronounced  and  becomes  nearly  due  north  and 
south  along  the  western  wall  of  the  valley  of  Big  Grand  Pierre  Creek.  In 
the  southeastern  portion  of  the  county,  as  may  be  seen  upon  the  accompany- 
ing geological  map  (Plate  I),  the  strike  of  the  rock  strata  again  exhibits  a 
slight  curvature  to  the  south,  a  direction  that  continues  as  the  formations  are 
traced  into  Kentucky. 

This  area  surrounded  by  the  Pottsville-Chester  boundary,  including 
Hardin  County  and  the  eastern  part  of  Pope,  is  roughly  semicircular  in  out- 
line, and  is  apparently  the  northwestern  border  of  a  dome-like  structure  of 
considerable  magnitude,  stretching  in  a  northwest-southeast  direction.  The 
extent  of  this  structure  into  Kentucky  and  the  completion  of  the  dome 
structure,  if  such  it  be,  cannot  be  determined  at  the  present  time,  and  must 
await  the  continuation  of  detailed  geologic  mapping  in  that  direction. 

The  explanation  of  the  dome  structure  indicated  by  the  attitude  of  the 
sedimentary  formations,  is  suggested  by  the  presence  of  the  igneous  dikes 
which  have  been  recognized  within  the  area.  These  dikes  are  known  in 
Hardin  County  and  in  the  southeastern  part  of  Pope  County,  and  others  are 
reported  from  Crittenden  County,  Kentucky,  the  actual  known  outcrops  of 
the  dikes  being  distributed  over  an  area  nearly  25  miles  in  length  in  a 
northwest-southeast  direction,  and  nearly  15  miles  in  width.  All  these  dikes 
are  similar  in  character,  and  are  undoubtedly  connected  with  a  deep  seated 
igneous  intrusion,  the  injection  of  which  into  the  rock  formations  has  up- 
warped  the  overlying  strata.  As  the  rocks  were  elevated  in  this  manner  they 
were  subjected  to  enormous  tension  or  stretching  forces  which  caused  them 
to  be  fractured  along  the  major  lines  we  now  recognize  as  faults. 

As  the  fault  blocks  lie  at  the  present  time,  many  of  them  have  slipped 
downward  from  the  position  they  occupied  when  the  dome  was  first  formed, 
this  downward  slipping  being  nearly  or  quite  1500  feet  in  some  places.  An 
adequate  cause  for  this  settling  of  the  dome  must  be  sought  for.    The  cooling 


STRUCTURAL   GEOLOGY  57 

of  the  igneous  material  and  consequent  contraction  would  occasion  a  certain 
amount  of  reduction,  but  it  would  be  entirely  inadequate  to  account  for  the 
very  extensive  collapse  of  the  dome.  A  much  more  competent  reason  for  the 
breaking  down  of  the  original  dome  may  be  found  in  the  gradual  spreading 
out  of  the  material  constituting  the  intrusion.  When  the  igneous  matter  was 
first  intruded  from  a  still  deeper  source,  it  was  very  hot  and  was  in  a  more 
or  less  liquid  condition.  It  required  an  exceedingly  long  period  to  become 
cooled  and  solidified,  and  during  this  whole  time  the  enormously  heavy  load 
of  sedimentary  beds  resting  upon  it  tended  to  squeeze  it  out  about  its 
periphery  into  and  between  the  overlying  strata.  The  result  of  the  action  of 
these  forces  would  be  to  reduce  the  height  of  the  dome  and  increase  its 
diameter.  With  the  transfer  in  this  manner  of  the  position  of  the  material 
which  supported  the  original  dome,  the  dome  itself,  or  at  least  sections  of  it 
would  of  necessity  break  down,  and  in  such  a  collapse  extremely  complicated 
faulting  would  result.  Some  basis  for  the  assumption  that  there  has  been  a 
spreading  out  and  consequent  flattening  of  the  original  igneous  mass,  is  the 
fact  that  at  least  one  good  exhibition  of  an  igneous  sill  or  horizontal  intrusion, 
has  been  observed  in  the  county.  This  sill  is  well  exposed  (see  figure  15)  in 
the  upper  portion  of  the  first  knob-like  hill  below  Eosiclare,  on  the  bank  of 
Ohio  Eiver. 

Another  possible  explanation  for  the  collapse  of  the  dome  supported  by 
the  intruded  igneous  mass,  might  be  the  withdrawal  of  some  portion  of  the 
molten  material  into  the  cavities  from  which  it  had  been  extruded  in  the 
first  place.  Either  one  of  these  reasons,  or  more  likely  a  combination  of 
the  two,  would  be  adequate  to  explain  the  phenomena  as  we  observe  them 
at  the  present  time. 

If  the  explanation  of  the  Hardin  County  structures  that  has  been 
suggested  is  the  correct  one,  then  the  smaller  dome  structure  exhibited  at 
Hicks  is  but  a  minor  feature  of  the  larger  dome,  although  at  the  present  time 
it  is  in  a  far  better  state  of  preservation  than  is  the  major  dome.  The  com- 
plicated fault  pattern  exhibited  in  Hardin  County  is  exactly  such  as  might 
be  expected  to  be  produced  under  the  conditions  that  have  been  outlined. 
The  extreme  northwestern  border  of  the  larger  dome  structure  is  quite 
perfectly  exhibited  in  the  northwestern  corner  of  the  county  and  in  the 
adjoining  portion  of  Pope  County.  A  belt  passing  obliquely  across  the 
county  from  northeast  to  southwest,  from  near  the  mouth  of  Saline  River 
to  the  vicinity  of  Rosiclare,  represents  a  segment  of  the  dome  which,  taken 
alone,  constitutes  a  great  arch,  and  is  one  of  the  segments  that  has  suffered 
extensive  collapse  with  the  settling  away  of  the  underlying  igneous  material. 
This  arch-like  segment  has  a  width  of  about  five  miles  in  a  northwest-southeast 
direction.  Its  northwestern  boundary  is  a  fault  line  that  passes  close  to 
Wolrab   Mill,   and   its   southeastern   boundary   is   formed   bv   a   fault   which 


58  GEOLOGY    OF    HARDIN    COUNTY 

extends  from  the  mouth  of  Hosick  Creek,  a  mile  and  one-half  east  of  Eliza- 
bethtown,  to  a  point  a  little  above  the  mouth  of  Saline  Eiver. 

This  faulted  area  is  in  reality  a  double  arch,  or  indeed  for  a  part  of  its 
distance  a  three-parted  arch,  the  belt  being  split  longitudinally,  the  south- 
eastern and  central  portions  being  more  deeply  depressed  and  more  completely 
collapsed  than  the  other  segments.  In  this  more  deeply  down-dropped  seg- 
ment, a  long  tongue-like  extension  of  the  Pottsville  formations  reaches 
southwest  from  the  northeastern  border  of  the  dome,  for  a  distance  of  nearly 
eight  miles  from  their  normal  position  of  outcrop.  A  similar  tongue-like 
extension  of  the  same  formations  reaches  in  a  northeasterly  direction  towards 
Eosiclare,  but  is  mostly  restricted  to  the  Kentucky  side  of  Ohio  Eiver.  This 
segment,  therefore,  even  after  its  collapse  still  retains  its  arch-like  form,  the 
higher  Pottsville  occupying  the  northeastern  and  southwestern  portions,  and 
the  older  Chester  formations  the  central  region. 

Most  of  the  faults  in  the  county  are  confined  to  the  belt  indicated  above. 
It  is  unnecessary  to  attempt  to  describe  in  detail  every  fault  in  the  county,  or 
to  give  the  evidence  upon  which  it  is  located,  since  their  locations  and  dis- 
placements are  shown  upon  the  areal  geological  map  (Plate  I)  ;  but  some  of 
the  more  important  ones  will  be  described  later.  The  field  criteria  which 
have  been  used  in  mapping  the  faults  have  been  of  various  sorts.  In  those 
situations  where  the  displacement  has  brought  limestone  and  sandstone  forma- 
tions into  juxtaposition  on  the  two  sides  of  the  fault,  the  determination  of 
the  fault  line  is  a  comparatively  simple  matter,  but  where  two  sandstones  are 
brought  together  the  problem  has  been  more  difficult  of  solution.  Very 
generally,  however,  the  positions  of  fault  lines  in  sandstone  are  indicated  by 
the  transformation  of  the  sandstone  into  quartzite,  accompanied  by  notable 
fracturing  of  the  quartzite.  Such  hard  quartzite  ledges  in  many  places  stand 
up  conspicuously  above  the  surrounding  rocks  because  of  their  greater  hard- 
ness, and  are  commonly  designated  as  "quartzite  reefs"  by  the  local  pros- 
pectors. Not  infrequently,  quartzite  is  found  along  some  of  the  fault  lines 
even  where  limestone  is  present  on  both  sides,  the  source  of  such  quartzite 
doubtless  being  some  overlying  sandstone  bed,  broken  blocks  of  which 
slipped  downward  into  fractures  formed  by  normal  faulting  under  tension 
strains.  Such  blocks,  on  being  crushed  between  hard  limestone  walls  became 
quartzitic  in  character  and  are  now  exposed  in  places  along  the  fault  lines. 
Such  an  exposure  of  quartzite  is  well  exhibited  along  the  road  on  the  ridge  in 
ATE.  Vi  sec.  7,  T.  12  S.,  E.  8  E.,  a  little  more  than  two  miles  east  of  Eichorn. 

When  the  softer  and  less  resistant  formations  adjoin  a  fault  on  either 
one  or  both  sides,  the  fault  itself  is  often  not  limited  to  a  plane  or  even  a 
narrow  zone,  but  the  break  is  likely  to  be  a  compound  fracture  with  the 
displacement  distributed  through  a  much  crushed  zone  which  in  places  may 
be  one  to  two  hundred  feet  or  more  in  width.     In  such  crushed  zone«,  dis- 


STRUCTURAL    GEOLOGY  59 

placed  masses  of  formations  different  from  those  on  either  side  of  the  fault, 
are  locally  present,  or  a  mass  of  the  formation  on  the  upthrow  side  may  be 
present  well  over  towards  the  opposite  edge  of  the  zone  at  a  much  lower  eleva- 
tion. Such  masses  occur  iri  places  a  little  outside  the  boundaries  of  the 
formations  as  shown  upon  the  map,  but  they  are  too  small  in  extent  to  be 
indicated  upon  the  scale  that  is  used  in  the  areal  map. 

Associated  with-  the  faults  in  all  sorts  of  rocks,  there  are  likely  to  be 
slickensided  surfaces,  which  are  the  smoothed,  polished,  and  scored  surfaces 
along  which  movement  between  rock  masses  has  taken  place.  As  seen  in 
'natural  exposures  the  slickensided  surfaces  are  commonly  restricted  in  extent, 
but  in  some  of  the  surfaces  uncovered  in  mining  operations  they  are  much 
'larger.  At  one  point  in  the  Kosiclare  mine  a  finely  slickensided  surface  many 
square  yards  in  extent  is  exhibited. 

The  presence  of  mineralized  veins  is  commonly  a  good  criterion  for  the 
location  of  faults  in  that  part  of  the  county  where  the  rock  strata  are  much 
fractured;  however  some  of  the  mineral  veins  are  certainly  not  along  fault 
jlines  but  are  situated  along  fractures  where  there  has  been  no  dislocation,  or 
are  secondary  fillings  of  solution  cavities  in  limestone,  particularly  in  the 
Ste.  Genevieve  limestone. 

Throughout  most  of  the  county  the  rock  strata  lie  in  a  nearly  horizontal 
position  or  exhibit  only  gentle  dips.  Steeply  clipping  strata,  however,  are 
locally  present,  and  where  they  do  occur  they  are  commonly,  if  not  always,  in 
close  proximity  to  fault  lines,  the  strike  being  approximately  parallel  to  the 
fault. 

The  presence  of  springs,  in  some  localities,  suggests  the  proximity  of 
fault  lines,  such  fracture  lines  in  many  places  apparently  being  open  courses 
through  which  the  ground  waters  circulate  and  come  to  the  surface. 

In  places  throughout  the  county,  especially  in  those  areas  occupied  by 
the  denser  limestone  formations  such  as  the  St.  Louis  and  the  Ste.  Genevieve, 
the  hard  limestone  exhibits  a  notable  amount  of  shattering,  the  fractures 
being  healed  with  milky  white  calcite.  Such  calcite  veins  commonly  occur 
near  fault  lines,  but  in  places  they  are  certainly  present  in  locations  where 
the  beds  have  been  subjected  to  strain  sufficient  to  fracture  them  but  not  to 
produce  dislocation  of  any  notable  amount. 

If  the  explanation  for  the  faulting  of  the  rocks  in  Hardin  County  that 
lhas  been  suggested  in  the  preceding  pages  is  the  correct  one.  then  the  actual 
■fractures  that  have  taken  place  occurred  during  two  different  periods  of  the 
same  process.  The  earliest  fractures  must  have  been  formed  during  the 
initial  updoming  of  the  region  by  the  intrusion  of  the  deep-seated  igneous 
mass.  Produced  by  the  tension  strains  due  to  the  stretching  of  the  crust 
above  the  intrusion,  they  would  doubtless  be  elongate  in  character,  more  or 
less  parallel  in  direction,  or  diverging  at  low  angles.     The  later  faults  would 


60  GEOLOGY    OF    HARDIN    COUNTY 

be  formed  during  the  period  of  collapse  of  the  dome  or  of  segments  of  the 
dome,  they  would  be  very  much  more  irregular  in  their  direction,  and  many 
of  them  would  be  short,  bounding  the  sides  of  the  small,  irregularly  shaped 
blocks  that  would  be  formed  during  the  progress  of  the  settling  of  the  frag- 
ments of  the  collapsing  portions  of  the  rock  mass. 

In  actual  experience  it  is  difficult  to  differentiate  between  the  faults 
which  may  have  been  formed  during  these  two  parts  of  the  process  involved, 
but  it  is  nevertheless  possible  that  recognition  of  the  two  sorts  of  faults  may 
have  an  important  bearing  upon  the  interpretation  of  the  mineral  deposits 
of  the  county.  Certain  of  the  faults  in  the  region  have  exhibited  evidence  of 
mineralization  at  various  points  along  their  courses,  and  we  may  assume  that 
they  are  more  or  less  mineralized  throughout  their  extent.  Other  faults  have 
nowhere  shown  any  evidence  of  mineralization,  and  probably  are  not  at  all 
mineralized.  It  is  possible  that  the  mineralized  and  the  non-mineralized 
faults  may  represent  on  the  one  hand  the  initial  faults  formed  with  the 
original  updoming  of  the  rock  strata,  and  on  the  other  hand  the  subsequent 
fractures  formed  during  the  later  collapse  of  the  arch.  Data  are  not  available 
at  the  present  time  for  the  demonstration  of  any  such  conclusion  as  that  which 
is  suggested,  and  it  probably  could  be  demonstrated  only  with  much  addi- 
tional mining  development.  If  in  the  future,  however,  the  suggestion  proves 
to  be  well-grounded,  the  differentiation  of  the  two  sorts  of  faults  may  come 
to  have  an  important  application  in  the  direction  of  further  mining 
development. 

The  diagonal,  much  faulted  zone  crossing  from  northeast  to  southwest, 
divides  the  county  into  three  distinct  regions,  the  faulted  zone  itself  being 
one  of  these,  and  the  areas  to  the  northwest  and  southeast  being  the  other 
two  (see  figure  3).  In  its  essential  features  this  central,  much  faulted  zone 
is  a  down  dropped  block  or  segment  of  younger  formations  lying  between  older 
rocks.  In  settling  to  its  present  position  the  dislocation  of  the  strata  did  not 
take  place  simply  along  two,  continuous  faults  bounding  the  two  sides  of  the 
segment,  but  the  fracturing  and  dislocation  was  exceedingly  complicated  in 
character.  In  general  the  central,  longitudinal  portion  of  the  zone  (belt 
number  two,  fig.  3)  has  settled  more  deeply  than  the  lateral  parts,  and  the 
total  dislocation  on  each  side  has  been  distributed  among  a  number  of  faults 
having  a  northeast-southwest  direction.  These  faults  are  not  all  straight 
and  parallel.  In  many  localities  a  single  fault  divides  and  continues  as  two 
whose  directions  diverge  at  a  low  angle,  bounding  a  narrow  wedge-shaped 
block  which  in  some  places  is  down-dropped  relative  to  the  strata  on  the  two 
sides,  elsewhere  on  one  side  only,  and  in  at  least  one  case  the  rocks  on  the 
both  sides  of  such  a  block  are  down-dropped  relative  to  the  block  itself. 
Some  of  these  wedge-shaped  blocks  are  also  much  broken,  especially  near  their 
extremities,  by  shorter  faults  whose  direction  is  more  or  less  transverse  to 


STEUCTUEAL   GEOLOGY 


61 


Fig.  3.— Map  showing  the  faults  and  the  structural  segments  of  Hardin  County. 


62  GEOLOGY    OF    HARDIN    COUNTY 

the  general  direction  of  the  longer  faults.  In  some  cases  two  diverging 
faults,  when  traced  for  some  distance,  again  converge  and  may  become 
joined,  in  which  case  they  enclose  an  elongate,  narrow  block,  acutely  pointed 
at  each  end.  The  apices  of  these  wedge-shaped  blocks  are  not  all  uniformly 
pointed  in  the  same  direction,  and  in  some  parts  of  the  county  there  is  a 
distinct  intei  fingering  of  the  blocks  pointing  in  opposite  directions. 

In  the  northeastern  third  of  the  central  faulted  zone,  the  entire  area  is 
divided  longitudinally  into  two  belts,  while  in  the  southwestern  two-thirds 
there  are  three  such  belts,  the  southeasternmost  belt  at  the  north  becoming 
the  middle  belt  toward  the  southwest.  For  convenience  in  discussion,  these 
three  belts  may  be  designated  by  the  numbers  one,  two,  and  three,  beginning 
with  the  belt  on  the  northwestern  border.  The  accompanying  map  (tig.  3) 
outlines  the  zones  and  belts. 

Belt  number  one  is  continuous  from  Saline  Eiver  to  the  Hardin-Pope 
county  line.  It  varies  in  width  from  three  miles  at  its  northernmost  ex- 
tremity to  scarcely  more  than  one  mile  near  Illinois  Furnace,  and  it  includes 
a  complete  sequence  of  the  strata  present  in  the  county  from  the  St.  Louis 
limestone  to  the  Tradewater  formation.  Like  the  faulted  zone  as  a  whole 
this  belt  is  in  the  form  of  an  arch,  in  which  the  older  formations,  the  St. 
Louis  and  Ste.  Genevieve  limestones,  occupy  the  greater  part  of  it?  central 
portion.  In  the  northern  limb  of  the  arch,  a  complete  section  of  the  Chester 
and  Pottsville  formations  is  represented,  but  in  the  southern  limb  only  the 
lowermost  Chester  formations  are  represented,  in  the  extreme  southwestern 
part  of  the  county.  The  belt  as  a  whole  is  not  so  complexly  broken  up  by 
minor  faults  as  is  belt  number  two,  but  there  is  faulting  south  of  Harris 
Creek,  towards  the  north,  and  also  both  east  and  west  of  Wallace  Branch  in 
the  southwestern  part  of  the  county. 

Belt  number  two  (see  figure  3)  includes  the  most  deeply  down-dropped 
portion  of  the  faulted  zone  as  a  whole,  being  constituted  almost  entirely  of 
rocks  of  Chester  and  Pottsville  age.  The  Ste.  Genevieve  limestone  is  present 
in  only  one  small  block  east  of  Stone  School,  and  the  St.  Louis  limestone  does 
not  anywhere  outcrop  at  the  surface.  In  the  northernmost  third  of  the 
faulted  zone,  belt  number  two  becomes  the  southeastern  border  of  the  zone, 
with  the  disappearance  of  belt  number  three,  and  is  somewhat  more  than  two 
miles  wide.  It  becomes  narrower  to  the  southwest  and  is  but  little  more  than 
one  mile  wide  at  Keelin  School.  At  about  the  position  of  Big  Creek  the 
direction  of  this  belt  deviates  slightly  and  becomes  more  southerly,  and 
although  there  is  not  a  great  difference  in  the  course  of  the  faulting  in  the  two 
directions  from  Big  Creek,  there  is  a  distinct  though  slight  elbow  exhibited, 
which  has  had  a  notable  influence  upon  the  complexity  of  the  faulting.  The 
northeasternmost  part  of  this  belt  consists  of  the  elongate,  tongue-like  mass  of 
Pottsville   sandstone  which   extends   for   a   distance   of   approximately   eight 


STRUCTURAL    GEOLOGY  63 

miles  in  a  southwesterly  direction  from  the  position  of  the  margin  of  the 
Pottsville  outcrop  on  either  side  of  the  zone.  Within  this  Pottsville  tongue 
no  extensive  faulting  has  been  worked  out,  although  one  fault  has  been 
mapped  northwest  of  Rock  Creek.  It  is  possible  that  the  block  is  more 
complexly  faulted  than  is  indicated  on  the  map,  for  in  the  Pottsville  forma- 
tions it  has  not  been  practicable  to  differentiate  the  beds  with  sufficient 
distinctness  to  make  possible  their  use  in  the  determination  of  fault  disloca- 
tions. Southwest  from  Keelin  School,  however,  beyond  which  point  the 
Chester  formations  constitute  most  of  the  surface  rocks  in  this  belt,  it  has 
been  possible  to  work  out  the  complex  faulting  with  a  considerable  degree  of 
success.  In  a  northeasterly  direction  from  Big  Creek,  the  general  direction 
of  the  more  continuous  faults  in  the  belt  is  X.  50°  E.,  while  to  the  southwest 
of  the  same  stream  the  general  direction  becomes  X.  25°  E.  These  is  more  or 
less  criss-crossing  of  the  faults  having  these  two  directions  in  the  region  where 
the  change  of  direction  takes  place,  a  circumstance  which  is  sufficient  to 
account  for  the  complexity  of  the  faulting  that  is  exhibited  for  a  distance  of 
two  miles  along  the  valley  of  Big  Creek,  north  from  Stone  School.  In  fact, 
the  position  of  this  part  of  Big  Creek  valley  has  doubtless  been  determined 
by  the  faulting,  the  excessive  fracturing  of  the  rocks  having  constituted  a  line 
of  weakness  along  which  the  stream  found  it  easiest  to  erode  its  channel. 

In  the  southwestern  part  of  the  county  the  very  resistant  Pottsville  rocks 
cap  two  large  hills  which  are  included  within  belt  number  two,  namely,  Stone 
Hill  situated  in  sees.  17,  18,  19,  and  20,  T.  12  S.,  R.  8  E.,  and  the  hill  lying 
between  Threemile  Creek  and  Wallace  Branch.  A  number  of  small  hills  east 
of  Threemile  Creek,  and  one  east  of  Wallace  Branch,  are  also  capped^  by  the 
same  rocks.  Xo  continuous  tongue  of  Pottsville  in  this  belt,  such  as  that 
extending  northeast  from  Keelin  School,  is  present  in  the  southwestern  part 
of  Hardin  County,  but  the  hills  capped  with  Pottsville  constitute  the  terminal 
portion  of  a  continuous  Pottsville  tongue  which  is  present  in  belt  number 
two  in  its  extension  to  the  southwest  into  Kentucky. 

Belt  number  three  of  the  faulted  zone  (see  figure  3)  is  not  continuous 
entirely  across  Hardin  County.  It  originates  in  sec.  33,  T.  11  S.,  R,  9  E., 
near  the  headwaters  of  Peters  Creek,  and  continues  in  a  southwesterly  direc- 
tion to  Rosiclare.  The  southeastern  boundary  of  this  belt  extends  from  its 
point  of  origin  to  the  mouth  of  Hosick  Creek  about  one  and  one-half  miles 
above  Elizabethtown.  In  its  narrower  northeastern  portion,  where  the  rock 
strata  exposed  are  of  Chester  age  the  belt  includes  a  number  of  narrowly 
elongate,  more  or  less  wedge-shaped  blocks.  In  its  extension  to  the  south- 
west it  is  less  broken  up  and  is  largely  made  up  of  the  Ste.  Genevieve  lime- 
stone. At  its  southwestern  extremity  in  Hardin  County,  the  lower  Chester 
formations  are  again  exposed  in  the  two  hills  on  the  Ohio  River  bank,  just' 
below  Rosiclare. 


64 


GEOLOGY  OF  HARDIN  COUNTY 


Very  little  evidence  is  available  concerning  the  amount  of  inclination  or 
hade  of  the  fault  planes,  because  extensive  mining  operations  have  been  con- 
ducted along  but  few  of  them.  The  Rosiclare  vein  is  practically  vertical  in 
position,  although  at  the  Good  Hope  shaft  of  the  Fairview  mine  it  inclines 
79°  30'  to  the  northwest.  At  the  Extension  shaft  of  the  same  mine,  which 
is  probably  on  the  same  fault,  the  shaft  has  been  sunk  vertically  to  the  depth 
of  425  feet  in  16  feet  of  vein  matter,  without  encountering  either  wall.  On 
the  other  hand  the  fault  along  which  the  workings  of  the  Blue  Diggings  mine 
have  been  conducted,  is  inclined  to  the  northeast,  in  places  at  as  low  an 
angle  as  45°,  and  at  greater  depths  than  have  yet  been  reached  in  mining,  it 
may  join  the  Eosiclare  fault  to  the  east  of  it. 

Relation  of  Topography  to  Geologic  Structure 
It  has  already  been  pointed  out  that  a  much  faulted  belt  crosses  Hardin 
County  diagonally  from  the  southwest  to  the  northeast  corner.  Within  this 
belt  the  major  faults  extend  in  a  northeast-southwest  direction,  and  their 
influence  upon  the  surface  configuration  is  clearly  shown  upon  the  topo- 
graphic map  of  the  county.  Such  faults  constitute  lines  of  weakness  in  the 
earth's  crust  along  which  drainage  courses  naturally  develop.  The  most 
important  streams  in  the  county  whose  direction  has  been  controlled  hy  fault 
structure,  are  Rock  Creek,  Hogthief  Creek  and  the  upper  portion  of  Peters 
Creek.  Many  lesser  tributaries,  both  of  the  creeks  mentioned  and  of  other 
creeks  that  penetrate  the  belt,  are  also  conspicuous  for  their  northeast- 
southwest  direction.  The  tributaries  of  Big  Creek  south  of  the  mouth  of 
Hogthief  clearly  show  this  structural  influence,  those  from  the  east  all 
entering  the  main  stream  from  the  northeast,  while  the  tributaries  from 
the  west  enter  the  main  stream  from  the  southwest.  The  more  or  less 
elongate,  sandstone-capped  hills  or  ridges  which  are  conspicuously  developed 
in  this  faulted  belt,  all  exhibit  a  northeast-southwest  trend,  essentially 
parallel  with  the  major  faults. 

Northwest  of  Elizabethtown,  the  much  faulted  zone  exhibits  a  slight 
change  of  direction,  the  general  trend  of  the  fault  lines  northeastward  from 
this  position  being  approximately  N.  50°  E.,  while  to  the  southwest  they 
are  more  nearly  N.  25°  E.,  as  has  been  said.  In  the  elbow  where  this  change 
of  direction  takes  place,  the  fault  zone  is  far  more  broken  up  by  cross  faults 
than  elsewhere,  and  it  is  through  this  much  fractured  part  of  the  belt,  which 
was  an  especial  line  of  weakness,  that  the  valley  of  Big1  Creek  has  been 
excavated  across  the  fault  zone.  No  other  large  creek  in  the  county  crosses 
the  faulted  belt,  and  had  not  the  great  amount  of  fracturing  of  the  rocks 
occasioned  this  line  of  weakness,  Big  Creek  doubtless  would  have  excavated 
its  channel  in  a  southwesterly  direction  from  near  the  mouth  of  Hogthief 
Creek,  and  would  have  entered  Ohio  River  west  of  Rosiclare,  perhaps  where 
Threemile  Creek  now  joins  the  river. 


structural  geology  65 

Hicks  Dome 

The  Hicks  Dome  is  an  oval  swell  or  uplift  of  strata  which  has  its  center 
in  sec.  30,  T.  11  S.,  E.  8  E.,  three-fourths  of  a  mile  southeast  of  Hicks.  The 
longer  axis  of  the  uplift  extends  in  a  northwest-southeast  direction,  passing 
through  Wolrab  Mill  and  the  SAY.  %  sec.  14,  T.  11  S.,  E.  7  E.  From  the 
center  of  the  dome  the  rocks  dip  outward  in  all  directions  through  a  circular 
belt  of  country  of  varying  width,  to  the  west  and  north  extending  beyond 
the  county  boundary.  The  outward  dip  of  the  rocks  is  exhibited  along  Hicks 
Branch  from  south  of  the  center  of  sec.  25,  T.  11  S.,  E.  7  E.,  to  Big  Grand 
Pierre  Creek.  In  the  southwestern  part  of  sec.  25  the  amount  of  dip  varies 
from  12°  to  30°  with  15°  as  a  fair  average,  as  shown  from  observations  upon 
the  Osage  chert  which  outcrops  along  Hicks  Branch  in  that  locality.  From 
sec.  25  westward  the  dip  as  determined  at  a  great  many  points  does  not  vaxy 
greatly  from  10°,  and  a  northward  dip  of  10°  prevails  around  the  north- 
western end  of  the  dome  within  the  county.  In  the  northeast-southwest 
direction  along  the  shorter  axis  of  the  oval,  the  dip  is  likewise  15°  to  20° 
outward  near  the  center  of  the  dome,  but  decreases  outward  so  that  at  a 
distance  of  one  and  one-half  to  two  miles  from  the  center  of  the  dome,  the 
dip  is  low  and  the  rocks  are  nearly  horizontal  in  position.  The  difference  in 
the  dip  manifests  itself  in  the  differences  in  width  of  the  outcrop  of  the 
Fredonia  oolitic  limestone.  Xorthwest  of  the  Hicks  Dome  the  outcrop  of 
the  Fredonia  with  a  dip  of  10°  is  about  one-third  of  a  mile  wide,  while  south- 
west and  northwest  of  the  dome  the  outcrop  is  fully  a  mile  wide  (see  Plate  I). 
This  distribution  illustrates  the  fact  that  the  less  the  angle  of  dip  the  greater 
will  be  the  width  of  outcrop.  To  the  northeast  the  dip  steepens  beyond  the 
north  margin  of  the  Fredonia  limestone  outcrop,  and  is  about  10°  across  a 
belt  about  one  mile  wide,  lying  mainly  in  the  second  tier  of  sections  south  of 
the  county  line.  North  of  this  belt  the  dip  decreases  to  about  5°  as  finely 
displayed  in  the  extensive  line  of  cliffs  dipping  northward  towards  the  syn- 
cline  of  Eagle  Valley,  which  lies  a  few  miles  north  of  the  county  line.  A 
profile  of  the  structure  northeast  of  the  dome,  starting  at  the  center,  would 
show  a  rather  steep  descent,  followed  by  a  gentle  descent  or  nearly  horizontal 
line  for  a  mile  or  so,  then  a  steeper  descent. for  three-fourths  of  a  mile,  and 
last  a  rather  gentle  descent  to  the  Eagle  Valley  syncline.  Along  the  northwest- 
southeast  axis  the  position  of  the  beds  and  structural  profile  are  exhibited  in 
section  A- A  on  the  geological  map,  Plate  I.  The  structure  of  the  region 
centering  in  the  Hicks  Dome  is  also  exhibited  by  the  map,  Plate  III,  on 
which  the  position  of  the  rocks  is  graphically  expressed  by  contours  showing 
the  actual  or  calculated  position  of  the  top  of  the  Chattanooga  shale  with 
reference  to  sea  level.  Outside  of  the  outcrop  of  the  Chattanooga  shale  near 
the  center  of  the  dome,  this  formation  lies  deep  below  the  surface,  and  its  top 


66  GEOLOGY  OF  HARDIN  COUNTY 

must  be  approximately  determined  by  the  thickness  of  the  overlying  strata; 
hence  the  contours  are  only  approximately  correct,  but  they  represent  well 
enough  the  general  structure  of  the  region,  and  probably  do  not  vary  any- 
where from  the  true  position  by  much,  if  any,  more  than  100  feet. 

To  the  southwest  of  the  Hicks  Dome,  in  the  country  between  Eichorn 
and  St.  Joseph  School,  the  strata  dip  gently  westward  to  the  county  line. 
This  part  of  the  county  is  also  more  or  less  broken  by  faults  which  offset 
and  more  or  less  interrupt  the  continuity  of  the  outcrops  of  the  formations. 

Herod  Fault 

The  Herod  fault  crosses  the  northwestern  corner  of  Hardin  County,  and 
takes  its  name  from  Herod  in  Pope  County,  about  one  mile  west  of  the 
Hardin-Pope  county  line.  In  Hardin  County  the  fault  has  a  displacement  of 
more  than  100  feet  downthrow  on  the  southeast,  but  it  increases  to  the 
southwestward.  The  fault,  or  rather  the  system  of  faults  into  which  it 
breaks  up,  has  been  traced  to  the  vicinity  of  Eeevesville  in  Johnson  County, 
20  miles  to  the  southwest. 

Lee  Fault 

The  Lee  fault  is  named  from  Lees  mine  in  the  northwest  corner  of 
sec.  14,  T.  11  S.,  E.  8  E.  This  fault  extends  northeastward  for  some  distance 
beyond  the  county  boundary,  and  has  been  traced  in  a  southwest  direction  to 
the  northwest  corner  of  sec.  21,  T.  11  S.,  E,  8  E.,  beyond  which  point  it 
probably  continues  into  the  limestone  mass  in  which  it  can  not  be  detected ; 
and  it  possibly  connects  across  the  Hicks  dome  with  the  Hobbs  Creek  fault 
which  continues  into  Pope  County,  although  there  is  no  discoverable  evidence 
of  such  an  extension.  The  displacement  along  this  fault  in  the  vicinity  of 
Lees  mine  is  about  400  feet,  the  strata  on  the  southeast  side  being  down- 
dropped  so  as  to  bring1  the  Glen  Dean  limestone  opposite  the  top  of  the 
Fredonia  oolite  in  the  center  of  sec.  15,  T.  11  S.,  E.  8  E.,  as  is  shown  on  the 
map.  The  throw  diminishes  to  the  southwestward  rapidly  and  in  the  north- 
east corner  of  sec.  20,  T.  11  S.,  E.  8  E.,  it  is  less  than  the  thickness  of,  the 
Fredonia  oolite  for  the  Eosiclare  sandstone  does  not  appear  to  have  been 
dropped  to  the  level  of  the  top  of  the  St.  Louis  limestone.  This  is  a  strong 
indication  that  the  fault  dies  out  in  that  direction,  as  indicated  by  the  broken 
line  on  the  map,  and  does  not  connect  across  the  Hicks  dome  with  the  Hobbs 
Creek  fault.  The  effect  of  the  downthrow  in  offsetting  the  outcrop  southward 
on  the  downthrow  side,  is  explained  by  the  north  dip  of  the  strata  and  the 
erosion  of  the  land  to  the  same  general  level. 

An  interesting  and  important  feature  of  the  Lee  fault  is  the  fluorspar 
vein  associated  with  it  in  the  vicinity  of  the  Lees  mine.  So  far  as  has  been 
determined  by  actual  mining  operations  the  more  important  fluorspar  veins 


STRUCTURAL   GEOLOGY  67 

in  the  county  are  located  along  fault  lines,  but  this  subject  will  be  more  fully 
treated  in  Chapter  XII. 

Wolrab  Mill  Fault 

The  Wolrab  Mill  fault  is  named  from  Wolrab  Mill,  near  which  it  passes. 
In  the  middle  part  of  its  course  this  fault  deviates  from  a  straight  line  or  an 
even  curve,  more  than  any  other  fault  in  the  county.  It  is  also  the  longe'st 
fault  in  the  county,  having  been  traced  from  beyond  the  northern  boundary 
southwest  across  the  western  boundary  into  Pope  County.  It  continues  to 
Grand  Pierre.  Creek  where  it  apparently  breaks  up,  but  is  really  continued 
as  another  fault  nearly  across  Pope  County  into  the  hills  south  of  the  Bay 
bottoms,  where  it  is  lost  a  little  before  reaching  the  Massac-Pope  county  line. 
The  downthrow  is  on  the  southeast  side,  about  205  feet  in  the  northern  part 
of  the  county,  but  it  becomes  less  to  the  southwest,  and  at  the  Pope  County 
line  the  throw  is  not  more  than  50  or  60  feet.  No  mineral  deposits  are  known 
along  the  fault  northeast  of  the  axis  of  the  Hicks  dome,  but  the  Stewart  mine 
in  the  southwestern  part  of  the  county  is  situated  upon  it. 

Block  Between  the  Wolrab  Mill  and  Hogthief  Creek  Faults 

The  Hogthief  Creek  fault  and  its  connected  continuation  faults  extends 
to  the  southwestern  corner  of  the  county,  and  the  block  between  it  and  the 
Wolrab  Mill  fault  is  a  shallow  syncline.  The  St.  Louis  limestone  dips  north- 
west 5°  to  7°  from  the  Hogthief  Creek  fault,  and  the  same  limestone  dips 
east  at  a  low  angle  on  the  southeast  limb  of  the  Hicks  dome  east  of  the  Wolrab 
Mill  fault.  At  least  one  fault,  which  may  be  called  the  Illinois  Furnace  fault, 
nearly  bisects  the  syncline  just  east  of  Big  Creek  and  Illinois  Furnace.  This 
fault  is  clearly  indicated  by  the  relations  on  the  opposite  sides  of  the  knob 
in  the  XE.  %  sec.  9,  T.  12  S.,  R.  8  E.,  where  the  old  iron  ore  diggings  were 
located.  In  this  hill  the  Fredonia  oolite  occupies  the  east  side  and  the  St;. 
Louis  limestone  the  west  side  at  the  same  level.  The  position  of  the  fault  is 
also  conspicuously  marked  at  the  road  intersection  in  XE.  14  SE.  %  sec.  4, 
T.  12  S.,  R.  8  E.  by  a  thick  calcite  vein  and  with  abundant  calcite  scattered 
about  in  the  road  and  ditches,  On  the  west  side  of  the  calcite  vein  dark 
limestone  with  Lithosiroiion  prolif&rum  outcrops,  while  just  to  the  east  and 
only  a  few  feet  higher  the  Rosiclare  sandstone  caps  the  ridge  showing  that  the 
fault  is  downthrown  on  the  east  about  150  feet  at  least.  It  is  not  improbable 
that  the  synclinal  tract  between  Hogthief  Creek  and  Wolrab  Mill  faults,  as 
far  to  the  north  as  Harris  Creek,  is  more  or  less  cut  by  fissures  along  some 
of  which  there  are  slight  displacements,  but  if  so  the  slips  are  small,  for  the 
Rosiclare  sandstone  has  a  practically  continuous  outcrop  across  the  block 
from  northwest  to  southeast. 


68  geology  of  hardin  county 

Hogthiep  Creek  Fault 

The  Hogthief  Creek  fault  is  named  from  that  creek,  the  south  side  of 
whose  valley  it  follows  for  three  miles.  This  is  one  of  the  long  faults  of  the 
county,  and  with  possibly  one  exception  it  has  the  greatest  displacement  of 
any.  Its  northern  end  has  not  been  certainly  determined,  but  no  evidence  has 
been  found  for  its  extension  beyond  the  east  side  of  sec.  10,  T.  11  S.,  E.  9  E., 
about  one-half  mile  north  of  Carrs  Store.  Like  the  faults  already  described, 
this  one  is  downthrown  on  the  southeast,  and  to  the  east  of  Hogthief  Creek 
the  displacement  is  fully  1200  feet,  so  that  the  bottom  of  the  Caseyville 
formation  is  dropped  down  to  the  level  of  the  St.  Louis  limestone.  The  throw 
decreases  to  the  northeast,  so  that  in  the  SW.  %  sec.  10,  T.  11  S.,  R.  9  E.,  the 
Caseyville  is  down  only  to  the  Glen  Dean  limestone,  the  displacement  prob- 
ably not  exceeding  500  feet.  Southwestwardly  the  fault  is  traceable  to  Big 
Creek  where  it  ends  in  the  remarkable  fault  complex  north  of  Stone  Church, 
although  its  displacement  is  continued  by  a  number  of  shorter,  more  or  less 
intricately  connected  faults,  to  Ohio  River  at  the  mouth  of  Wallace  Branch 
near  the  southwestern  corner  of  the  county.  No  mineral  deposits  have  been 
discovered  along  this  fault. 

Rock  Creek  Fault 

A  little  north  of  its  mid-length,  in  sec.  30,  T.  11  S.,  R.  9  E.,  the  Hogthief 
Creek  fault  divides,  the  two  branches  diverging  at  a  low  angle  for  about  two 
miles  to  the  northeast  and  then  becoming  nearly  parallel.  These  two  branches 
form  the  boundaries  of  one  of  the  characteristic,  elongate,  narrowly  wedge- 
shaped  fault  blocks  which  are  so  frequent  in  Hardin  County,  the  block  being 
down  dropped  relative  to  the  areas  on  either  side  of  it.  The  northernmost  of 
the  two  branches  is  considered  as  the  continuation  of  the  Hogthief  Creek 
fault  because  the  downthrow  along  this  line  is  on  the  southeast  side  through- 
out. The  southern  branch  may  be  known  as  the  Rock  Creek  fault,  and  along 
this  line  of  displacement  the  downthrow  is  on  the  northwest.  It  extends  into 
sec.  15,  T.  11  S.,  R.  9  E.,  where  it  is  buried  by  alluvium  and  cannot  be  traced 
farther.  In  sec.  21,  T.  11  S.,  R.  9  E.,  the  bottom  of  the  Caseyville  formation 
in  the  wedge-shaped  block  between  the  two  faults,  is  dropped  considerably 
below  the  Glen  Dean  limestone  so  that  the  displacement  is  over  500  feet  and 
probably  at  least  700  feet.  Where  this  fault  passes  near  and  south  of  the  road 
in  the  sections  named,  there  is  an  excellent  exhibition  of  the  highly  inclined 
quartzite  ledges  usually  associated  with  the  faults  where  they  cut  sandstone, 
and  bearing  witness  of  their  presence.  These  quartzite  ledges  are  hard,  much 
fractured  and  slickensided.  At  the  place  described  there  seem  to  be  two  or 
more  parallel  ledges  of  quartzite  in  a  width  of  100  feet  or  so,  as  if  there 
were  more  than  one  break  along  which,  movement  has  taken  place,  which  was 
probably  the  case. 


structural  geology  69 

Faults  a  Short  Distance  North  of  the  Hogthief  Creek  Fault 

Between  the  Hogthief  Creek  fault  and  Goose  Creek  there  are  two  parallel 
straight  faults  connected  by  a  minor  oblique  fault  in  sees.  16,  17,  20,  and  19, 
T.  11  S.,  E.  9  E.  The  southernmost  of  the  parallel  faults  seems  to  branch 
off  westward  from  the  Hogthief  Creek  fault  in  the  southwest  corner  of  sec. 
16.  These  faults  manifest  themselves  very  plainly  at  several  points  on  ravines 
and  along  the  banks  of  streams,  by  crushed  and  otherwise  disrupted  and 
slickensided  quartzite  ledges.  One  of  the  best  exhibitions  of  these  fault 
phenomena  is  in  the  bed  of  the  ravine  in  the  NW.  Vi  sec.  30,  T.  11  S.,  E.  9  E., 
where  some  large  slickensided  quartzite  boulders  are  lying  loose  upon  the 
surface,  and  where  the  contorted  shale  and  sandstone  is  exposed  for  several 
hundred  feet  along  the  bed  and  banks  of  the  stream.  The  cross  fault  extend- 
ing from  sec.  25,  T.  11  S.,  E.  8  E.,  and  into  sec.  19,  T.  11  S.,  E.  9  E.,  is  in- 
ferred from  the  presence  of  the  Menard  limestone  in  the  ravine  and  hillside 
just  to  the  east  and  the  Bethel  and  Cypress  sandstones  with  the  Paint  Creek 
shale  between  on  the  hilltop  and  slopes  in  the  eastern  part  of  sec.  24,  T.  11 
S.,  E.  8  E.  These  relations  could  be  brought  about  only  by  a  fault  between 
the  ravine  and  the  hilltop,  but  its  exact  location  has  not  been  determined. 

Peters  Creek  Faults 

Along  the  upper  two-thirds  of  the  course  of  Peters  Creek  there  are  four 
subparallel  or  slightly  diverging  faults  named  from  the  stream.  The  four 
separate  faults  in  the  group  may  be  designated  by  the  letters  A,  B,  C,  and  D, 
beginning  with  the  southernmost  one.  So  far  as  can  be  determined  all  of 
them  unite  near  the  boundary  line  between  sees.  33  and.34;  T.  11  S.,  E.  9  E., 
and  continue  as  a  single  fault  to  the  northeast  which  can  be  traced  into  the 
alluvium  of  sec.  13,  T.  11  S.,  E.  9  E.  The  downthrow  is  on  the  north  side 
of  each  of  these  faults  and  the  accumulated  effect  north  of  Peters  Creek  is 
a  doAvnthrow  of  1,000  feet  or  more,  nearly  the  full  thickness  of  the  Chester 
group.  The  two  southern  faults  of  the  group,  A  and  B,  diverge  constantly 
to  the  southwestward.  Fault  A  has  been  continued  on  the  map  on  rather 
slender  evidence,  to  Ohio  Elver  at  the  mouth  of  Hosick  Creek,  and  fault  B 
is  certainly  recognized  to  the  center  of  sec.  23,  T.  12  S.,  E.  8  E.,  where  it  is 
exhibited  in  a  recently  opened  prospect  hole,  beyond  which  point  it  probably 
dies  out.  The  wedge  shaped  block  between  these  two  members  of  the  Peters 
Creek  fault  group  is  broken  up  by  a  number  of  minor  faults  in  sees.  7,  8,  and 
18,  T.  12  S.,  E,  9  E.  Fault  C  of  the  group  has  been  assumed  to  be  the 
boundary  line  between  belts  two  and  three  of  the  central  faulted  zone  of  the 
county.  By  reason  of  their  divergence  from  their  point  of  departure  in  sec. 
33,  T.  11  S.,  E.  8  E.,  and  their  convergence  and  union  again,  a  little  over  six 
miles  to  the  southwest,  faults  C  and  D  of  the  Peters  Creek  group  enclose  a 


70  GEOLOGY    OF   HARDIN    COUNTY 

very  narrow,  elongate  fault  block  in  which  the  Chester  formations  from  the 
Bethel  sandstone  to  the  Tar  Springs  sandstone  are  exposed. 

Where  the  Peters  Creek  faults  continue  to  the  northeast  as  a  single 
fault,  a  small  amount  of  mineralization  has  occurred,  but  no  profitable  mineral 
deposits  have  been  developed.  The  Martin  and  Eureka  prospects,  where  a 
small  amount  of  lead  and  zinc  have  been  found,  are  located  on  this  fault  in 
sec.  23,  T.  11  S.,  E.  8  E.  Along  the  several  faults  of  the  group,  southwest  of 
the  point  of  breaking  up  of  the  single  fault,  a  number  of  rather  deep  prospect 
holes  have  been  sunk,  either  on  the  fault  lines  or  in  the  adjacent,  crushed, 
quartzite  zones,  but  no  ore  of  importance  has  yet  been  found.  The  mineral 
deposits  in  the  vicinity  of  Lead  Hill,  in  sec.  4,  T.  12  S.,  R.  9  E.,  lie  one-half 
mile  or  so  southeast  of  the  Peters  Creek  fault  A,  and  there  may  be  some  con- 
nection between  this  mineralization  and  the  faults,  but  such  a  relation  has  not 
been  established. 

Rosiclare  Fault 

The  Rosiclare  fault  originates  near  the  middle  of  the  line  between  sees. 
16  and  21,  T.  12  S.,  R.  8  E.,  and  continues  in  a  southwesterly  direction 
through  the  Rosiclare  and  Fairview  mines.  Its  continuation  across-  Ohio 
River  into  Kentucky  has  not  been  traced.  It  crosses  the  highway  near  the  top 
of  the  hill  at  the  turn  in  the  road  a  little  over  one-half  mile  west  of  the  iron 
bridge  over  Big  Creek  near  Elizabethtown.  The  downthrow  along  this  fault 
is  on  the  northwest  side,  the  dislocation  at  Rosiclare  being  about  200  to  250 
feet,  bringing  the  basal  portion  of  the  Bethel  sandstone  on  the  southeast, 
against  some  portion,  probably  the  upper  part,  of  the  Cypress  sandstone.  At 
the  point  where  the  fault  crosses  the  road  as  indicated  above,  the  amount  of 
throw  is  greatly  reduced,  because  at  that  place  the  structural  block  lying  west 
of  the  fault — which  is  a  somewhat  irregular  triangular  mass  of  moderate 
size — forms  a  notable  exception  to  other  similar  blocks  in  the  region,  in  that 
it  has  remained  elevated,  relatively,  while  all  of  the  surrounding  blocks  have 
dropped  downward  during  the  readjustment  which  took  place  at  the  time  of 
the  complex  fracturing.  In  most  cases  in  this  region,  such  triangular  blocks 
have  dropped  lower  than  the  surrounding  masses. 

An  important  feature  of  the  Rosiclare  fault  is  its  rich  mineralization. 
The  Rosiclare  and  Fairview  mines  are  the  only  two  extensively  developed 
fluorspar  mines  in  the  entire  southeastern  Illinois  district,  and  the  main 
shafts  and  workings  of  both  of  these  mines  are  situated  upon  this  fault.  In 
both  of  these  mines  the  mineralization  has  been  shown  to  continue  to  a 
depth  of  500  feet;  how  much  farther  it  extends  can  be  determined  only  by 
further  development  and  explanation.  Other  smaller  mines  have  been  opened 
and  worked  along  the  same  fault  from  time  to  time,  and  although  they  have 
shown  more  or  less  extensive  mineralization,  they  have  not  been  fully 
developed. 


structural  geology  71 

Daisy  Fault 

The  Daisy  fault  is  named  from  the  Daisy  mine.  This  fault  is  really  a 
branch  of  the  Rosiclare  fault,  the  two  diverging  to  the  southwest  from  a 
point  in  sec.  29,  T.  12  S.,  R.  8  E.,  south  of  the  road  from  the  Big  Creek  bridge 
to  Stone  School.  The  exact  point  of  departure  of  the  two  faults  is  not  clearly 
established  by  the  surface  outcrops,  but  it  must  lie  somewhere  in  the  northern 
half  of  the  section  mentioned.  The  block  between  the  two  faults  is  a  narrowly 
elongate,  wedge-shaped  mass,  less  than  one-fourth  mile  in  width  except  at 
its  southern  extremity;  it  is  occupied  by  the  Cypress  sandstone  throughout 
its  entire  extent  at  the  surface.  At  the  northeastern,  pointed  extremity  of 
the  wedge,  where  it  lies  in  contact  with  the  relatively  elevated  triangular 
block  that  has  been  mentioned  in  the  description  of  the  Eosiclare  fault, 
the  downthrow  of  the  Daisy  fault  is  to  the  southeast,  but  southward  from  the 
southern  extremity  of  this  triangular  block  the  dislocation  is  just  opposite, 
with  the  downthrow  on  the  northwestern  side.  At  the  Daisy  mine  the  dislo- 
cation must  be  between  150  and  200  feet,  becoming  somewhat  less  as  the 
fault  is  followed  to  the  southwest.  This  fault  continues  across  Ohio  River 
into  Kentucky,  where  it  may  be  clearly  seen  in  the  exposures  on  the  river 
bank  at  Carrsville.     The  fault  is  richly  mineralized  at  the  Daisy  mine. 

Blue  Diggings  Fault 

The  Blue  Diggings  mine  of  the  Fairview  Fluorspar  and  Lead  Company, 
is  situated  upon  a  fault  which  cannot  be  traced  from  surface  outcrops  be- 
cause of  the  surflcial  covering,  and  because  the  Cypress  sandstone  is  present 
on  both  sides  of  it.  At  the  shaft  it  lies  only  a  few  rods  east  of  the  Daisy 
fault,  and  if  it  were  possible  to  follow  it  north  to  its  origin,  it  would  doubtless 
join  the  Daisy  fault,  or  perhaps,  though  less  probably,  the  Rosiclare  fault. 
This  fault  is  a  fracture  in  the  main  block  lying  between  the  Rosiclare  and 
Daisy  faults,  but  unlike  the  nearly  vertical  Rosiclare  fault,  it  has  a  dip  in 
places  as  low  as  45°  to  the  east,  and  if  followed  to  greater  depths  than  have 
been  reached  at  this  time  in  any  mining  operations,  it  would  perhaps  be 
found  to  join  the  Rosiclare  fault.  It  bounds  one  side  of  a  wedge-shaped 
block  which  has  settled  a  little  lower  than  the  adjacent  block  to  the  west, 
between  this  fault  and  the  Daisy  fault.  The  zone  immediately  ajacent  to  the 
fault  plane  on  the  east  has  been  very  greatly  fractured  as  is  shown  in  figure  28. 

Big  Creek  Fault 

This  fault  passes  very  close  to  the  road  corner  at  Carmens  Store,  and  a 
few  rods  west  of  Stone  Church.  It  is  sub-parallel  with  the  Daisy  and  Rosi- 
clare faults,  and  lies  a  little  less  than  one-half  mile  west  of  the  Daisy  fault. 
It  has  a  much  greater  extent  longitudinally  than  either  of  the  two  other 


72  GEOLOGY  OF  HARDIN  COUNTY 

faults  mentioned,  its  length  from  Hogthief  Creek  in  NE.  %  sec.  9,  T.  12  S., 
E.  8  E.,  to  Ohio  River  being  approximately  six  miles.  It  may  perhaps  be 
considered  as  the  master  fault  through  the  complexly  faulted  district  along 
Big  Creek,  north  of  Stone  Church,  a  circumstance  that  has  suggested  its 
name,  and  it  is  the  termination  of  both  the  Hogthief  Creek  fault  and  the 
main  Peters  Creek  fault  from  the  northeast.  In  the  main  the  dislocation 
along  the  Big  Creek  fault  shows  the  downthrow  on  the  northwest  side,  and 
opposite  Rosiclare  this  dislocation  is  approximately  350  feet,  bringing  the 
top  of  the  Golconda  limestone  opposite  the  top  of  the  Menard.  In  the 
northern  half  of  its  course,  where  it  passes  through  the  complexly  faulted 
district,  it  separates  numerous  small,  triangular  or  irregular  shaped  blocks 
whose  movements  have  varied  in  the  downward  adjustment  during  the  period 
of  deformation,  so  that  between  some  of  the  blocks  the  downthrow  is  on  one 
side,  while  elsewhere  it  is  on  the  opposite  side.  The  fault  continues  across 
Ohio  River  into  Kentucky,  where  it  passes  between  Carrsville  and  the  point 
of  the  bluff  on  the  Ohio  just  west  of  the  town. 

Comparatively  little  prospecting  lias  been  done  along  this  fault.  One 
shaft  is  being  sunk  near  its  northern  extremity,  in  SE.  *4  SW.  %  sec.  9,  T. 
12  S.,  R.  8  E.,  where  some  mineralization  is  shown,  but  the  work  has  not  yet 
progressed  beyond  the  prospecting  stage.  In  view  of  the  rich  mineralization 
of  the  Rosiclare  and  Daisy  faults  in  the  vicinity  of  Rosiclare,  it  would  seem 
that  the  Big  Creek  fault  might  also  be  mineralized  towards  Ohio  River,  but 
the  determination  of  such  a  condition  can  be  established  only  by  more  or  less 
extensive  prospecting  work. 

Illinois  Furnace  Fault 

The  Illinois  Furnace  fault  has  already  been  mentioned  in  connection 
with  the  description  of  the  block  between  the  Wolrab  Mill  and  Hogthief 
Creek  faults  earlier  in  the  chapter.  It  bisects  the  hill  south  of  Hogthief 
Creek,  opposite  the  old  Illinois  Furnace,  and  continues  in  a  southwesterly 
direction  past  the  northwest  face  of  Stone  Hill,  and  terminates  against  the 
fault  that  will  be  described  as  the  Threemile  Creek  fault,  in  the  SW.  % 
sec.  19,  T.  12  S.,  R.  8  E,  Structurally  this  fault,  with  the  Wallace  Branch 
fault  to  be  described  later,  is  a  continuation  of  the  Hogthief  Creek  fault 
farther  to  the  northeast,  although  neither  of  these  faults  actually  joins  this 
northeastern  extension  which  terminates  at  the  Big  Creek  fault.  The  dislo- 
lation  along  the  Illinois  Furnace  fault  exhibits  downthrow  on  the  southeastern 
side,  the  line  of  dislocation  like  that  of  the  Hogthief  Creek  fault,  being  the 
northwestern  boundary  of  the  most  deeply  downdropped  central  belt  of  the 
faulted  zone  of  the  county.  The  amount  of  dislocation  varies  at  different 
points  along  the  fault  line  because  some  of  the  several  blocks  which  are 
adjacent  to  it  on  the  southeast  side  have  dropped  deeper  than  others  in  the 


STRUCTURAL   GEOLOGY  73 

period  of  readjustment  of  the  blocks.  The  greatest  dislocation  is  at  the 
northern  corner  of  Stone  Hill,  in  the  NE.  %,  sec.  17,  T.  12  S.,  R.  8  E.,  where 
the  lower  beds  of  the  St.  Louis  limestone  lie  opposite  the  lower  part  of  the 
Pottsville,  giving  a  slip  of  approximately  1,600  feet,  which  is  probably  the 
maximum  dislocation  in  the  county.  The  amount  of  dislocation  decreases 
somewhat  in  a  southwestward  direction,  and  at  the  termination  of  the  fault 
in  that  direction  amounts  to  about  1,100  feet,  the  Clore  formation  on  the 
southeast  being  in  contact  with  the  Fredonia  on  the  northwestern  side  of 
the  fault. 

The  Illinois  Furnace  fault  is  known  to  be  mineralized  at  a  number  of 
points,  but  the  prospecting  work  that  has  been  done  along  this  line  has  not 
been  sufficient  to  determine  the  extent  of  the  mineralization.  A  small  mine 
was  opened  at  one  time  at  the  northern  corner  of  Stone  Hill  in  the  XE.  % 
sec.  17,  T.  12  S.,  R,  8  E.,  but  it  has  been  abandoned  for  a  number  of  years. 
More  recently  some  prospecting  has  been  clone  farther  southwest  along  the 
fault,  by  the  owners  of  the  Eosiclare  mine,  but  this  work  too,  has  been 
abandoned  for  the  present. 

Threemile  Creek  Fault 

The  Threemile  Creek  fault  has  been  so  named  because  some  mining 
operations  have  been  conducted  along  it  at  the  point  where  it  crosses  Three- 
mile  Creek  in  the  SW.  %  sec.  19,  T.  12  S.,  R.  8  E.  It  branches  off  from  the 
Big  Creek  fault  in  the  west  %  of  sec.  16,  T.  12  S.,  R.  8  E.,  and  continues  in 
a  southwesterly  direction  past  the  southeastern  face  of  Stone  Hill,  and  past 
the  southern  termination  of  the  Illinois  Furnace  fault,  across  the  Wallace 
Branch  fault  to  the  Pell  fault  along  Wallace  Branch,  in  the  west  %  °f  sec- 
25,  T.  12  S.,  R,  7  E.  Through  most  of  its  length  the  downthrown  block 
lies  on  the  northwestern  side  of  the  fault,  but  beyond  the  termination  of  the 
Illinois  Furnace  fault,  in  a  southwestward  direction,  the  downthrown  block 
lies  on  the  southeastern  side.  Whatever  mineralization  has  been  recognized 
along  this  fault  occurs  at  and  near  the  point  where  it  crosses  Threemile 
Creek,  near  where  a  number  of  faults  come  together,  as  is  shown  on  the 
geological  map  (Plate  I).  A  number  of  prospect  holes  have  been  sunk  at 
this  locality,  but  no  real  development  work  has  ever  been  attempted. 

Wallace  Branch  Fault 

The  Wallace  Branch  fault  is  really  a  continuation  of  the  Illinois 
Furnace  fault,  offset  about  one-third  of  a  mile  to  the  west  at  the  Threemile 
Creek  fault.  The  fault  originates  in  the  SW.  %  sec.  19,  T.  12  S.,  R.  8  EL, 
and  continues  in  a  southwesterly  direction  to  the  valley  of  Wallace  Branch, 
past  the  southeastern  side  of  Rich  Hill,  to  Ohio  River  near  the  mouth  of 
Wallace  Branch.     Except  at  its  extreme  northeastern  extremity,  where  this 


74  GEOLOGY  OF  HARDIN  COUNTY 

fault,  the  Threemile  Creek  fault,  and  a  third  unnamed  fault  surround  a 
small,  triangular  block  of  sandstone  that  is  probably  Bethel,  the  dislocation 
along  the  Wallace  Branch  fault  is  represented  by  the  downdropping  of  the 
block  to  the  southeast.  In  the  lower  portion  of  Wallace  Branch  valley  the 
dislocation  amounts  to  1,100  or  1,200  feet,  but  it  is  considerably  less  than 
this  farther  to  the  northeast. 

Mineralization  has  been  recognized  along  this  fault  just  west  of  Wallace 
Branch  opposite  Melcher  Hills,  very  near  its  junction  with  a  fault  extending 
nearly  straight  north  along  Wallace  Branch,  towards  the  Pell  mine.  Con- 
siderable prospecting  has  been  carried  on  at  this  point,  but  the  deposits  have 
not  yet  been  commercially  exploited. 

Pell  Fault 

The  Pell  fault  extends  north  from  the  Wallace  Branch  fault,  alon| 
AVallace  Branch  valley  to  the  neighborhood  of  the  Pell  mine  in  NW.  %  sec. 
24,  T.  12  S.,  E.  7  E.,  beyond  which  point  it  seems  to  die  out.  It  seems  to  be 
one  of  those  lateral  faults  which  have  branched  off  from  one  of  the  more 
continuous  lines  of  fracture.  The  downthrow  is  on  the  east  side  of  the  fault 
and  grows  progressively  less  to  the  north.  The  wedge-shaped  area  lying 
between  the  Wallace  Branch  and  Pell  faults  furnishes  a  good  example  of  the 
more  or  less  complicated  fracturing  which  is  commonly  developed  in  such 
situations  throughout  the  fault  zone  in  Hardin  County. 


■.^' 


Shetlerville  Fault 

The  Shetlerville  fault  marks  a  line  of  slight  dislocation  which  doubtless 
branches  off  from  the  Wallace  Branch  fault,  about  as  the  Pell  fault  does,  but 
the  junction  point  lies  south  of  the  Ohio  and  so  is  not  shown  on  the  Hardin 
County  map.  The  fault  passes  just  east  of  Shetlerville  and  continues  in  a 
direction  a  little  west  of  north,  crossing  the  Hardin-Pope  county  line  in  the 
northwestern  corner  of  sec.  26,  T.  12  S.,  R.  7  E.  It  continues  northwest  into 
Pope  County  where  it  apparently  terminates  at  the  Wolrab  Mill  fault. 

Minor  Faults 

Besides  the  faults  that  seem  to  be  worthy  of  names,  and  of  somewhat 
detailed  descriptions,  there  are  many  others  in  the  district,  commonly  shorter 
than  those  that  have  been  described,  and  for  the  most  part  extending  trans- 
versely between  some  of  the  longer  ones.  Faults  of  this  character  which 
bound  blocks  that  are  variable  in  shape  but  tend  to  be  triangular  or  more 
or  less  rhomboidal,  and  wThich  vary  in  size  from  only  a  few  acres  to  nearly  a 
square  mile,  are  particularly  characteristic  oil  a  district  along  Big  Creek, 
between  the   Peters   Creek   and   the   Illinois   Furnace  faults.     As   has   been 


STRUCTURAL    GEOLOGY  75 

ointed  out  already,  this  complexly  faulted  area  is  situated  in  a  region  where 
le  longer  and  more  continuous  faults  exhibit  a  slight  change  in  their  direc- 
;on,  and  it  was  undoubtedly  due  to  the  complex  strains  that  were  developed 
1  connection  with  this  change  in  direction  of  the  major  faulting,  that  the 
reat  intricacy  of  the  minor  faults  was  produced.  A  not  uncommon 
henomenon  in  this  and  other  complexly  faulted  districts  in  the  county  is 
lie  development  of  faults  that  intersect,  like  the  two  lines  in  the  letter  X. 
n  some  cases  the  direction  of  throw  along  the  fault  line  changes  beyond 
he  point  of  intersection,  but  such  a  relation  is  not  exhibited  in  every  case, 
imong  faults  generally,  throughout  the  world,  intersecting  faults  of  this 
art  are  not  common  phenomena.  The  suggested  interpretation  of  the  area, 
owever,  namely,  the  up-bulging  of  the  crust  by  reason  of  the  deep-seated 
atrusion  of  an  igneous  mass,  and  a  later  collapse  of  the  dome  so  formed, 
Tould  seem  to  afford  the  conditions  that  would  account  for  the  formation  of 
aults  of  this  sort. 


PART  III 
STRATIGRAPHIC  GEOLOGY 


CHAPTEE  V— PRE-DEVONIAN 

By  Stuart  Weller  and  Chas.  Butts 


The  succession  of  stratified  rocks  exposed  at  the  surface  in  Hardin  County 
consists  of  a  series  of  limestones,  sandstones,  and  shales,  extending  from  the 
Middle  Devonian  limestone  below,  to  the  Tradewater  formation  of  the  Penn- 
sylvanian  system   at  the  summit.     The   sequence   of  these  formations,   and 
their  classification  and  arrangement  into  groups  and  systems,  are  shown  in 
the  accompanying  table.     The  lowest  of  these  rock  formations  was  deposited 
first,  many  millions  of  years  ago,  and  is  the  oldest,  each  succeeding  higher 
formation  being  younger.     Even  the  youngest  of  the  formations,  however,  is 
very   old,   for   since    its   deposition   thousands   of   feet   of   younger   rocks   of 
Mesozoic  and  Cenozoic  ages  have  been  deposited  in  various  parts  of  the  earth, 
of  which  there  are  no  representatives  in  this  region.     The  Rocky  Mountains 
have  been  formed  in  western  America  since  the  youngest  rocks  in  Hardin 
County  were  deposited,  and  the  strata  of  the  Himalaya  Mountains  in  southern 
Asia  have  been  deposited  and  then  raised  to  the  height  of  30,000  feet  since 
he  growth  of  the  Rocky  Mountains.     The  Hardin  County  region  has  prob- 
bly  been  dry  land  during  most  or  the  whole  of  Mesozoic  and  Cenozoic  time. 
Although  the  Middle  Devonian  limestone  is  the  oldest  formation  exposed 
n  Hardin  County,  the  region  is  certainly  underlain  by  rocks  of  greater  age. 
n  some  regions  deep  mine  shafts  have  been  sunk,  or  deep  wells  have  been 
rilled  which  give  information   concerning  rock  formations  which   are   not 
xposed  at  the  surface,  but  in  Hardin  County  no  deep  excavations  or  drilling 
has  supplied  any  such  information.     The  deepest  mine  shafts  do  not  pene- 
trate rocks  which  are  older  than  those  exposed  at  the  surface  within  the 
ounty.     The  only  evidence  available  at  this  time  bearing  upon  the  presence 
oi  rocks  older  than  those  exposed  at  the  surface,  is  found  in  the  pebbles  of 
various  sorts  which  are  included  in  a  dike  which  is  exposed  in  the  Ohio  River 
J)ank  at  Jenkins  Point,  about  one  mile  above  Rosiclare.     These  pebbles  are  of 
various   sorts,   quartzites,   limestones,   and   shales   being  represented.      These 
fragments  must  have  been  derived  from  formations  through  which  the  igneous 
ntrusion  passed  in  rising  to  the  level  now  exhibited,  and  some  of  them,  at 
least,  are  of  rock  types  which  are  not  represented  in  any  of  the  formations 
now  exposed  at  the  surface  within  the  county.     One  fragment  of  dark  shale 
crom  the  dike  has  preserved  a  portion  of  a  trilobite,  too  imperfect  for  de- 
ermination,  but  of  a  sort  not  known  from  any  of  the  surface  formations.    A 

79 


80  GEOLOGY   OF   HARDIN    COUNTY 

Table  1. — Classification  of  rocks  in  eastern  United  States  and  southern  Illinois 


General  time  scale 


Era 


C  en  o  zoic 

'Recent  life" 

(Age  of  mammals) 


Mesozoic 

"Middle  life" 

(Age  of  reptiles) 


Paleozoic 
"Ancient  life" 
(Era  of  inverte- 
brate animals 
and  non- 
flowering  plants) 


Period 

System 


Quaternary 


Tertiary 


Cretaceous 

Comanchean 

Jurassic 

Triassic 


Permian 


Pennsylvanian 

(Coal  Measures) 


Mississippian 


Epoch 
Group 


Recent 
Pleistocene 


Pliocene 

Miocene 

Oligocene 

Eocene 


Dunkard 


Pottsvillt 


PL! 


J. 

—  — 

=:  £ 

z  - 

-z 

Pm 


Chester 


So 


Devonian 


Silurian 


Ordovician 


Meramec 


Osage 


Kinderhook 


Upper 
Devonian 


Middle 
Devonian 


Lower 
Devonian 


Cambrian 


General  section  for  eastern 
United  States 


Formations 


Monongahela 
Conemangh 
Allegheny 


Homewood 

Mercer 

Connoquenessing 

Sharon 


Lykens  coal  Nos. 

]  and  2 

Anthracite  basin,  Pa. 

Sewell,  W.  Va. 


Lykens  coal  Nos. 

4  and  5 

Anthracite  basin,  Pa. 

Pocahontas,  W.  Va. 

Alabama  "Coal  Measures' 


Kinkaid 
Degonia 

CI  ore 

Palestine 

Menard 

Waltersburg 

Vienna 
Tar  Springs 


Glen  Dean 

Hardinsburg 

Golconda 

CvDress 


Paint  Creek 

Yankeetown 

Renault 

Aux  Vases 


Ste.  Genevieve 


St.  Louis 
Spergen 
Warsaw 


Keokuk 
Burlington 


Various  local 

formations  in 

Mississippi  Valley 


Catskill 
Chemung 
Portage 
Genesee 


Hamilton 

Mareellus 

Onondaga 

(Corniferous) 


Oriskany 
Helderberg 


Section  for  Hardin  and  Pope 
Counties,  Illinois 


Formations 


Surficial  deposits 


Absent 


Absent 


Absent 


Absent 
Absent 
Absent 


Tradewater 
Caseyville 


PossiblvCaseyville? 


Absent? 


Kinkaid 
Degonia 

Clore 
Palestine 
Menard 

Waltersburg 
Vienna 

Tar  Springs 


Glen  Dean 

Hardinsburg 

Golconda 

Cypress 


Paint  Creek 
Bethel 
Renault 

Shetlerville 
Absent 


Ste.  Genevieve 


St.  Louis 

Spergen 

Warsaw 


Osage 


Absent  or  upper 

part  of  Chatta- 

nooga  shale 


Absent? 

Chattanooga 
shale 


Limestones 

of  Devonian 

age  of  Hicks 

Dome 


Members 


Upper  Ohara' 


: Lower  Ohara' 
Rosiclare 
Fredonia 


Possibly  in 

lower  part  of 

Devon  ion  limestone 

of  Hicks  Dome 


Not  exposed 


Not  exposed 


Not  exposed 


PKE-DEVONIAN  81 

very  common  type  of  pebble  included  in  the  dike  rock  is  a  purple  quartzite. 
The  lithologic  character  of  these  quartzites  is  not  unlike  that  of  some  of  the 
pre-Cambrian  quartzites  which  are  known  as  surface  outcrops  in  various 
localities  in  North  America  far  to  the  north  of  Hardin  County.  The  quartzite 
pebbles  in  the  dike  are  well  rounded  and  have  every  appearance  of  being 
water  worn  in  origin,  and  they  may  have  been  picked  up  by  the  lava  rising  in 
the  dike  from  some  conglomerate  formation  in  which  pebbles  of  this  sort 
were  present.  In  the  Sparks  Hill  plug,  limestone  pebbles  with  fossil  bryozoa, 
doubtless  of  Mississippian  age,  are  not  uncommon;  but  these  of  course,  are 
not  older  than  rocks  exposed  in  surface  outcrops. 

The  oldest  sedimentary  rocks  exposed  in  the  county  are  restricted  in  their 
areal  distribution  to  the  central  portion  of  the  Hicks  dome,  around  which 
younger  formations  exhibit  a  ring-like  distribution. 

If  we  judge  from  our  knowledge  of  the  stratigraphic  succession  in  other 
portions  of  the  Mississippi  and  Ohio  valleys,  there  are  formations  representa- 
tive of  all  the  major  geological  systems  below  the  Devonian,  present  in  the 
earth's  crust  beneath  Hardin  County.  The  actual  formations  that  are  present 
are  of  course  unknown,  and  the  total  thickness  of  strata  down  to  the  Pro- 
terozoic  cannot  be  determined,  but  there  are  doubtless  several  thousand  feet. 


-6  G 


CHAPTER  VI— DEVONIAN 

By   Chas.   Butts  and   Stuart  Weller 


General  Statement 

The  Devonian  sediments  in  the  Ohio  Valley  have  their  best  development 
in  southeastern  Indiana  and  southwestern  Ohio,  on  the  opposite  sides  of  the 
Cincinnati  anticline,  and  the  exposures  in  Hardin  County  are  undoubtedly 
continuous  with  those  of  southeastern  Indiana,  beneath  the  overlying  younger 
sediments.  In  a  westerly  direction  the  Devonian  strata  outcrop  in  the  Mis- 
sissippi Valley  in  Jackson,  Union,  and  Alexander  counties,  Illinois,  and  in 
Ste.  Genevieve  County,  Missouri,  and  the  Hardin  County  beds  are  doubtless 
continuous  in  that  direction  as  well  as  to  the  east,  beneath  the  younger 
formations.  The  Hardin  County  section,  therefore,  is  a  sort  of  connecting 
link  between  the  sections  in  southern  Indiana  and  those  of  southwestern 
Illinois  and  southeastern  Missouri.  In  point  of  distance  the  Hardin  County 
area  is  much  nearer  to  southwestern  Illinois  than  to  the  Indiana  area. 

In  all  three  of  the  areas  mentioned  the  Devonian  section  consists  of  an 
important  black  shale  formation  whose  Devonian  age  has  been  questioned  by 
some  geologists,  underlain  by  limestones.  In  Indiana  and  the  adjacent  parts 
of  Kentucky,  the  limestone  series  below  the  black  shale  has  long  been  recog- 
nized as  of  Middle  Devonian  age,  and  many  fossils  have  been  described  from 
the  "Falls  of  the  Ohio"  from  both  the  "Upper  Helderberg"  or  "Corniferous," 
and  the  "Hamilton."  The  first  satisfactory  differentiation  of  the  Middle 
Devonian  strata  of  the  Indiana  section  was  made  by  Kindle1  who  applied  the 
name  Jeffersonville  limestone  to  the  lower  or  Onondaga,  and  Sellersburg  to 
the  upper  or  Hamilton  part  of  the  series. 

The  limestone  beds  beneath  the  black  shale  in  southwestern  Illinois  also 
have  been  shown  to  include  strata  equivalent  to  both  the  Hamilton  and  the 
Onondaga  formations  of  the  New  York  series2,  and  in  addition  still  older 
formations  of  Lower  Devonian  age.  Keyes3  suggested  the  name  Grand  Tower 
limestone  for  the  Middle  Devonian  strata  "below  those  beds  containing  the 
fossils  of  the  western  Hamilton."  Since  there  are  no  "western  Hamilton" 
faunas  in  the  Grand  Tower  section,  the  name  as  originally  given  would  seem 
to  be  applicable  to  the  whole  of  the  Middle  Devonian  section  at  that  locality. 


iBull.  Amer.   Pal.,  vol.   3,  p.   8    (1899). 

2Weller,  Jour.  Geol.,  vol.   5,  pp.   625-635    (1897)  ;  also  Savage,  Trans.   111.   State  Acad. 
Sci..  vol.   3,  pp.  116-132    (1910). 

3  Mo.  Geol.  Surv.,  vol.  4,  p.  42   (1894). 

83 


84  GEOLOGY    OF    HARDIN"    COUNTY 

Savage  has  amended  the  definition  of  the  formation  to  include  "only  that 
portion  of  the  Devonian  strata  of  southwestern  Illinois,  and  adjacent  parts  of 
Missouri,  which  is  the  western  representative  of  the  Onondaga  limestone  of 
New  York." 

The  Hardin  County  exposures  are  limited  in  extent,  and  outcrop  in  only 
the  one  locality,  namely  immediately  southeast  of  Hicks  on  the  summit  of  the 
Hicks  dome,  where  the  dome-shaped  upward  bulge  of  the  rocks  has  permitted 
the  overlying  formations  to  be  worn  away  so  as  to  expose  the  Devonian  strata 
in  the  center.  The  fossils  which  have  been  found  in  the  Devonian  limestones 
of  Hardin  County,  were  not  collected  from  the  beds  in  place.  The  species 
that  have  been  identified  indicate  the  presence  of  strata  of  both  Hamilton 
and  Onondaga  age,  the  Sellersburg  and  Jeffersonville  of  the  Indiana  section, 
and  the.  Grand  Tower  and  overlying  beds  in  southwestern  Illinois.  In  addi- 
tion to  these  there  are  some  forms  which  have  been  previously  recorded  only 
from  the  Clear  Creek  chert  of  southwestern  Illinois,  a  formation  which  is 
commonly  considered  as  late  Lower  Devonian  in  age.  Since  it  is  not  prac- 
ticable to  differentiate  these  Devonian  limestone  beds  in  Hardin  County,  they 
are  treated  together  under  the  head  "Limestone  of  Devonian  age." 

Limestone  of  Devonian  Age 

areal  distribution 

Outcrops  of  the  Devonian  limestone  in  Hardin  County  occupy  an  oval  area 
in  sections  30  and  31,  T.  11  S.,  E.  8  E.,  and  in  the  eastern  part  of  sec,  25, 
T.  11  S.,  E.  7  E.,  the  entire  area  being  about  one  square  mile  in  extent. 
Exposures  of  the  limestone  are  very  few  and  it  is  known  almost  wholly  from 
its  chert  which  is  abundant  upon  the  surface  underlain  by  the  limestone. 

LITHOLOGIC    CHARACTER 

So  far  as  known  the  Devonian  limestone  is  rather  coarsely  crystalline  and 
medium  dark  gray.  Limestone  of  this  character,  a  few  feet  thick,  is  exposed  at 
the  mouth  of  a  large  ravine  at  the  south  end  of  the  dome  in  the  NE.  %  sec.  31, 
T.  11  S.,  E.  8  E.,  and  similar  limestone  was  penetrated  at  a  depth  of  about  50 
feet  in  the  shaft  of  the  fluorspar  prospect  on  the  Eose  farm  about  one-fourth 
of  a  mile  southeast  of  Hicks  School.  At  the  Eose  prospect,  about  20  feet  of 
medium  thick-bedded  chert  is  now  exposed  in  the  upper  part  of  the  pit, 
dipping  about  30°  N.  A  considerable  quantity  of  limestone  has  been  thrown 
out  of  the  pit  and  is  now  mixed  with  the  chert  and  earth  on  the  dump.  The 
preceding  statement  gives  all  the  knowledge  that  has  been  obtained  of  the 
bed  rock  of  the  Devonian  limestone  in  the  county.  In  addition  the  presence: 
of  the  limestone  below  the  surface  is  indicated  by  much  chert  scattered  upon 
the  ground.     The  chert  is  gray  and  compact,  and  tends  to  assume  blocky  or 


DEVONIAN  85 

rounded  forms.  From  its  presence  the  rocks  below  have  formerly  been  re- 
garded as  Mississippian  and  the  same  as  the  rocks  outcropping  on  the  ridges 
surrounding  the  valleys  occupied  by  the  Chattanooga  (black)  shale,  since  these 
ridges  are  also  thickly  strewn  with  chert.  The  cherts  of  the  two  areas;  can 
readily  be  distinguished,  however.  The  Devonian  chert  takes  rounded,  blocky, 
or  irregular  forms  and  much  of  it  is  highly  or  fairly  fossiliferous,  while  the 
Mississippian  chert  is  distinguished  by  angular,  smooth-faced  pieces,  many 
of  which  are  striped  with  narrow,  pinkish  or  yellowish  bands,  and  fossils  are 
very  scarce.  So  far  as  known  at  present,  this  Devonian  formation  is  com- 
posed of  limestone  which  is  commonly  silicified  to  chert  near  the  surface,  as 
indicated  by  the  abundance  of  loose  chert  upon  the  ground,  and  also  by  the 
bedded  chert  just  below  the  surface  at  the  Rose  prospect.  It  is  not  improbable 
that  the  limestone  is  prevailingly  thus  silicified  on  the  outcrop  but  remains 
in  its  original  condition  as  limestone  at  no  great  depth. 

STRATIGRAPIIIC    RELATIONS 

The  Devonian  limestone  underlies  the  Chattanooga  (black)  shale  but  it 
is  not  known  what  is  beneath  the  limestone  in  this  region  since  the  underlying 
rocks  are  nowhere  exposed. 

THICKNESS 

No  direct  measurement  of  the  thickness  of  the  Devonian  limestone  of 
Hardin  County  is  possible  owing  to  the  absence  of  exposures.  The  thickness 
can  be  calculated  only  by  projecting  over  the  Hicks  dome  the  boundary  surface 
between  the  limestone  and  the  Chattanooga  shale  as  done  in  section  AA. 
Assuming  a  regular  curvature  to  this  surface,  it  would  pass  about  250  feet 
above  the  highest  knobs  near  the  center  of  the  area  of  outcrop  of  the  lime- 
stone, and  about  350  feet  above  the  bottoms  of  the  adjacent  ravines.  As  the 
limestone  apparently  extends  to  the  bottoms  of  the  ravines  its  thickness  should 
therefore  be  in  the  vicinity  of  350  feet. 

PALEONTOLOGY 

The  Devonian  chert  scattered  over  the  area  of  the  Hicks  dome  is  fairly 
fossiliferous  but  the  fossils  are  mostly  in  a  fragmentary  and  otherwise  poorly 
preserved  condition.  A  list  of  the  forms  either  certainly  or  doubtfully  identi- 
fied is  given  below : 

List  of  fossils  from  the  Devonian  limestone 

Cyathophyllum     rugosnm     Hall,  or         Michelinia    cf.    M.    stylopora    Eaton? 

Acervularia  davidsoni  E.  &  H.  Dolatocrinus    sp. 

Cystiphyllum  sp.  Hexacrinus   leai    (Lyon) 

Heliophyllum  sp.  Nucleocrinus   verneuili    (Troost) 


86  GEOLOGY  OF  HARDIN  COUNTY 

List  of  fossils  from  the  Devonian   limestone — Continued 
Atrypa  spinosa  Hall?  Spirifer  duodenarius  Hall 

Amphigenia  curta    (M.   &  W.)  Spirifer  gregarius  Clapp? 

Camarotoechia    tethys    (Billings)?  Spirifer  iowensis   Owen? 

Chonetes    coronatus    (Conrad)  Spirifer  segmentum  Hall 

Eatonia  sp.  Spirifer   varicosum   Hall 

Leptaena   rhomboidalis    (Wilck)  Spirifer    cf.    worthenanus    Schuchert. 

Meristella  haskinsi   Hall?  Very  close  to  S.  concinnus  in  form 

Schuchertella   arctistriata    (Hall)  and    number    of    ribs    and    exactly 

Spirifer  audaculus    (Conrad)?  the   same    in    ornamentation 

Spirifer  divaricatus  Hall  Tentaculites  bellulus  Hall 

Of  the  species  listed  Hexacrimis  leai,  Nucleocrvn.ua  vemeuili,  Camaro- 
toechia tethys,  Spirifer  divaricatus,  Spirifer  duodenarius,  Spirifer  gregarius, 
Spirifer  varicosus,  and  Spirifer  segmentum  are  recorded  only  from  the  Onon- 
daga (Corniferons)  limestone,  (Grand  Tower  limestone  of  Union  and  Jackson 
counties,  Illinois,  and  Jeffersonville  limestone  of  Kentucky  and  Indiana) 
except  that  Spirifer  duodenarius  occurs  also  in  the  upper  10  feet  of  beds 
assigned  to  the  Clear  Creek  chert  (Oriskany)  of  Union  County,  Illinois. 

Amphigenia  curta  and  Spirifer  worthenanus  are  recorded  only  from  the 
Clear  Creek  chert  of  Union  County.  The  genus  Eatonia  is  not  elsewhere 
known  above  the  Oriskany,  except  a  form  identified  as  Eatonia  occurs  at 
Grand  Tower,  Illinois,  where  it  is  recorded  by  Weller  in  the  lower  YtV^  feet 
of  beds  assigned  by  him  to  the  Grand  Tower  (Onondaga)  limestone.  Pro- 
fessor Weller  now  thinks,  however,  the  fossil  does  not  belong  to  the  genus 
Eatonia.  Michelinia  sUjlopora  is  identified  from  the  Clear  Creek  chert.  It 
would  seem  reasonable  that  the  Michelinia  of  the  Hardin  County  Devonian  is 
the  same  as  that  of  Union  County.  Michelinia  stylopora,  however,  is  a  Hamil- 
ton form  originally  described  from  the  Hamilton  of  Erie  County,  New  York. 
Most  of  the  other  species  or  genera  either  occur  in  the  Hamilton  or  at 
least  not  below  it.  Chonetes  coronatus  especially  is  considered  a  good  index 
fossil  of  the  Hamilton.  On  the  basis  of  the  fossil  evidence  therefore,  as 
usually  interpreted  in  Illinois,  the  Devonian  limestone  of  the  Hicks  dome  may 
include  representatives  of  Oriskany  time  as  well  as  those  of  Onondagan  and 
Hamilton  time,  which  it  surely  does  include.  However,  the  beds  in  the  upper 
part  of  the  Clear  Creek  chert  containing  Amphigenia.  curta,  Spirifer  worthen- 
anus, and,  in  Union  County,  other  brachiopods,  probably  should  be  regarded 
as  Onondaga  rather  than  as  Oriskany.  There  would  remain  only  the  Eatonia 
to  indicate  the  presence  of  the  Oriskany,  and  as  the  specimen  found  was  near 
the  bottom  of  a  ravine  in  which  the  lowest  stratigraphic  horizon  would  be 
exposed,  it  is  not  impossible  that  50  feet  or  so  of  genuine  Oriskany  outcrops 
in  the  deeper  ravines  on  the  summit  of  the  Hicks  dome.  The  thickness  of 
350  feet  is  ample  to  include  any  thickness  of  beds  of  Hamilton  and  Onondagan 
as  well  as  most  of  those  of  Oriskany  age  known  in  Illinois.  In  Union  County 
the  Hamilton  equivalent  is  given  as  70  feet,  the  Marcellus  as  28  feet,  the 


DEVONIAN  87 

Onondaga  (Grand  Tower  limestone)  as  156  feet,  and  the  Oriskany  (Clear 
Creek  chert)  as  237  feet,  a  total  of  490  feet.  Assuming  thicknesses  to  be  the 
same  on  the  Hicks  dome,  the  Devonian  beds  there  could  extend  nearly  150 
feet  into  the  Oriskany.  As  it  is  clearly  impossible  under  the  conditions  to 
separate  the  several  components  of  the  Devonian  here,  they  have  been  treated 
together  under  the  head  "Limestone  or  Devonian  Age." 

It  is  of  interest  that  a  vein  of  high  grade  fluorspar  occurs  in  the  Devonian 
limestone  and  probably  in  the  Hamilton  part  of  it,  on  Goose  Creek  about  one 
mile  southeast  of  Hicks,  where  it  has  been  prospected  and  worked  to  some 
extent  on  the  Rose  property.  The  vein  is  apparently  a  replacement  of  the 
limestone  layers  and  lies  parallel  to  the  bedding.  The  inclosing  beds  are 
chert  which  also  is  a  replacement  of  the  limestone  layers. 

Chattanooga  Shale 
name  and  distribution 

A  widespread  black  shale  formation  has  long  been  recognized  by  geological 
workers  in  Michigan,  Ohio,  Kentucky,  Tennessee,  Alabama,  Georgia,  Indiana, 
Illinois,  southern  Missouri,  Arkansas,  and  Oklahoma.  The  earlier  writers 
commonly  referred  to  this  formation  as  the  "Devonian  black  shale/'  but 
several  geographic  names  have  been  applied  to  it  by  different  workers.  As 
early  as  1861  Winchell1  included  this  black  shale  as  the  lower  member  of  his 
Huron  group.  In  southern  Ohio  the  member  was  called  the  "Ohio  black 
shale"  by  Andrews2  in  1870.  In  Indiana  Borden3  applied  the  name  New 
Albany  shale  to  the  formation  in  1874.  Many  of  the  earlier  writers  were 
inclined  to  correlate  the  shales  with  the  Genesee  shale  of  the  New  York  De- 
vonian section,  a  name  which  has  been  used  not  infrequently  in  the  literature 
discussing  the  formation.  When  the  black  shale  was  recognized  in  northern 
Arkansas  it  was  named  Eureka  shale  by  Simonds4  in  1888.  In  1890  Hayes5 
applied  the  name  Chattanooga  to  the  formation  in  Tennessee,.  In  1904 
Adams6  pointed  out  the  fact  that  the  name  Eureka,  used  by  Simonds  and 
others  for  the  black  shale  in  Arkansas,  was  preoccupied  for  a  formation  in 
Nevada,  and  thereupon  proposed  to  substitute  the  name  Noel  shale  for  the 
black  shales  in  northern  Arkansas  and  southern  Missouri. 

From  this  great  array  of  names  it  is  difficult  to  select  the  one  which 
should  properly  be  applied  to  the  formation  as  it  occurs  in  Hardin  County. 
The  IT.  S.  Geological  Survey  has  consistently  used  the  name  Chattanooga  in 
the  many  folio  publications  issued,  covering  areas  south  of  Ohio  Eiver,  and 
extending  as  far  west  as  Oklahoma.  This  name  is  not  the  earliest  one  pro- 
posed for  the  formation,  but  is  rather  one  of  the  later  ones;  however  it  has 

*lst  Bien.  Rep.  Prog-.,  Geol.  Surv.  Mich.,  p.  71    (1861). 

2  Geol.    Surv.   Ohio,   Rep.   of  Progress.    1869,   p.   62    (1870). 

3  5th  Ann.  Rep.  Ind.  Geol.  Surv.,  p.   158    (1874). 

4  Ark.  Geol.  Surv.,  1888,  vol  4,  pp.   26-27    (1888). 
9  Bull.  Geol.  Soc.  Amer.,  vol.  2,  p.  143    (1890). 

6U.  S.  Geol.  Surv.,  Prof.  Paper  No.   24,  p.   24    (1904). 


88  GEOLOGY   OF    HARDIN"    COUNTY 

been  more  widely  applied  than  any  other  and  may  be  adopted  for  the  Hardin 
County  exposures. 

In  Hardin  County  the  Chattanooga  shale  outcrops  only  in  the  vicinity 
of  Hicks,  in  a  rudely  circular  belt  of  country  from  one-fourth  to  one-third  of 
a  mile  in  width,  surrounding  the  area  of  the  Devonian  limestone  of  the  Hicks 
dome,  and  following  strictly  the  headwater  valleys  of  Goose  Creek. 

LITHOLOGIC   CHARACTERS 

The  Chattanooga  is  a  black,  carbonaceous,  fissile  shale  with  occasional 
non-fissile  layers  a  foot  or  so  in  thickness.  Such  non-fissile  layers  are  in- 
cluded in  the  outcrop  on  Goose  Creek  in  the  northeast  corner  of  sec.  31,  T.  12 
S.,  E.  8  E.  The  specimens  that  have  been  carefully  examined,  including 
specimens  of  very  fissile  layers  from  near  the  top,  and  of  the  thicker,  non- 
fissile  layers  near  or  below  the  middle,  are  highly  siliceous,  evidently  being 
composed  in  large  proportion  of  very  fine  quartz  grains.  In  some  parts  of 
the  formation  small  amounts  of  pyrite  are  present,  together  with  occasional, 
very  hard,  concretionary  bodies  that  are  more  or  less  pyritiferous.  The  upper- 
most ten  feet  or  so  of  the  formation  is  a  thin-bedded,  green,  argillaceous 
sandstone,  the  green  color  being  due  to  the  presence  of  glauconite,  some  of  the 
layers  appearing  to  be  half  glauconite  in  small  grains.  Upon  weathering, 
the  shale  loses  its  deep  black  color,  becoming  brownish  and  finally  grayish  in 
color,  and  splits  readily  into  thin,  laminar  fragments. 

thickness        y 

The  thickness  of  the  Chattanooga  in  the  region  appears  to  have  been 
underestimated  in  previous  accounts  at  50  to  100  feet.  The  best  determina- 
tion of  thickness  can  be  made  at  the  road  intersection  in  the  line  between 
sec.  36,  T.  12  S.,  R.  7  E.  and  sec.  31,  T.  12  S-.,  R.  8  E.,  one-fourth  mile  south 
of  the  north  line  of  the  sections.  Here  the  shale  is  almost  continuously  exposed 
from  the  top  contact  with  the  Osage  chert  above,  for  600  feet  across  the  strike 
to  the  northlwest.  The  dip  is  20°  to  the  southwest.  This  would  give  a  thick- 
ness of  220  feet  to  which  must  be  added  50  feet,  the  difference  in  elevation 
between  the  top  and  the  lowest  beds  exposed,  making  the  total  thickness 
exposed  270  feet.  But  the  bottom  of  the  shale  is  not  shown  and  shale  is 
reported  to  occur  on  the  slopes  across  the  valley  to  the  northwest.  Assuming 
the  shale  to  extend  to  the  foot  of  this  slope  the  width  of  the  outcrop  would 
be  at  least  1,000  feet,  which  with  a  dip  of  20°  would  make  the  thickness  364 
feet,  and  by  adding  the  difference  in  altitude  between  the  top  and  bottom, 
which  is  80  feet,  the  total  thickness  of  444  feet  is  obtained.  It  is  believed, 
therefore,  that  the  thickness  is  reasonably  estimated  at  400  feet.  This  would 
allow  for  some  variation  in  the  dip  which  might  reduce  the  average  below 
the  20°  observed  across  the  exposed  part  of  the  shale. 


DEVONIAN"  89 


PALEONTOLOGY 


The  Chattanooga  shale  in  Hardin  County  is  almost  devoid  of  fossils. 
Mr.  Weller  has  found  a  single  specimen  of  the  Phyllocarid  crustacean  Spathio- 
caris,  very  similar  to  or  identical  with  Spathiocmis  emersoni  Clarke.  As 
originally  described  this  species  is  recorded  from  the  Upper  Devonian  Portage 
formation  of  New  York,  where  it  is  said  to  be  widely  distributed  in  the  Naples 
beds,  and  in  the  upper  sandstone  of  the  formation.1  Examples  of  a  species 
identical  with  the  form  in  the  Chattanooga  shale  in  Hardin  County  have  been 
collected  by  Weller  in  the  Sweetland  Creek  shale  of  Iowa,  and  in  a  greenish 
shale  overlying  the  black  shale  in  southwestern  Missouri.  Mr.  Butts  has  col- 
lected from  the  glauconitic  sandstone  at  the  top  a  brachiopod  shell,  probably 
a  Leptaena  or  Pliolidostropliia,  a  fragment  of  a  shell  suggesting  a  Bellerophon, 
and  a  plumose,  carinated  fragment  suggestive  of  a  conodont  or  the  fringed 
tip  of  a  crustacean  spine,  like  the  telson  spine  of  Acanthotelson  ereni, 

CORRELATION 

The  Chattanooga  shale  of  Hardin  County  is  supposed  to  include  the 
equivalent  of  the  Chattanooga  of  the  type  locality — Chattanooga,  Tennessee — 
but  it  must  include  much  more  than  that  for  at  Chattanooga  the  shale  is  only 
20  to  30  feet  thick.  From  Chattanooga  this  characteristic  black  shale  has 
been  traced  practically  all  the  way  to  Hardin  County,  being  of  course  covered 
up  by  overlying  formations  in  extensive  areas.  The  black  shale,  however, 
always  appears  in  outcrop  wherever  its  horizon  is  exposed,  so  that  there  is  no 
doubt  whatever  of  its  continuity  as  a  great  sheet  spread  over  the  entire  region 
from  Birmingham,  Alabama,  northwestward  to  the  Mississippi  Valley.  In 
Ohio,  and  at  New  Albany,  Indiana,  Ulrich  thinks  the  main  body  of  the  black 
shale  is  Mississippian  and  equivalent  to  the  Kinderhook  of  the  Mississippi 
Valley,  while  admitting  that  the  lower  few  feet  is  of  Devonian  and  probably 
of  Genesee  age,  that  is  of  the  same  age  as  the  Genesee  black  shale  of  the 
Genesee  Valley  in  New  York.  The  general  scarcity  of  fossils  in  the  formation 
everywhere,  together  with  more  or  less  uncertainty  as  to  the  stratigraphic 
range  of  such  as  have  been  found,  makes  the  determination  of  its  age  uncer- 
tain.     In   Hardin    County   it   lies   between   limestone    of    Middle   Devonian 

(Hamilton)  age  below,  and  chert  of  Osage  age  above,  and  might,  therefore,  be 
either  Upper  Devonian  (Genesee,  Portage,  Chemung)  or  lower  Mississippian 

(Kinderhook),  or  it  may  be  partly  one  and  partly  the  other. 

STRATIGRAPHIC    RELATIONS 

If  the  Kinderhook  group  of  the  Mississippian  is  absent  in  Hardin 
County,  there  is  a  stratigraphic  gap  or  unconformity  between  the  Chattanooga 

1Hall  and  Clarke,  Pal.  N.  Y.,  vol.  7,  p.   200    (1888). 


90 


GEOLOGY  OF  HARDIN  COUNTY 


shale  and  the  overlying  Osage  chert.  If  the  Kinderhook  is  represented  by 
the  Chattanooga  there  is  an  unconformity  between  the  Chattanooga  and  the 
Middle  Devonian  limestone  below  it,  and  this  unconformity  would  mean  that 
the  whole  of  the  Upper  Devonian,  aggregating  many  thousand  feet  in  thick- 
ness, is  absent  in  southern  Illinois.  If  the  upper  and  larger  part  of  the 
Chattanooga  is  Kinderhook,  and  the  lower  part  Genesee,  then  there  is  a  great 
unconformity  in  the  midst  of  the  formation,  in  which  most  of  the  Upper 
Devonian  is  absent. 


CHAPTEE  VII— LOWER  MISSISSIPPIAN 

By  Chas.   Butts  and   Stuart  Weller 


General  Statement 

The  Mississippian  and  succeeding  Pennsylvania!!  systems  have  been 
esignated  as  series  by  many  writers,  instead  of  systems,  and  have  been 
•rouped  together!  as  the  Carboniferous  system.  There  are  ample  reasons, 
owever,  such  as  the  general  character  of  the  rocks,  their  thickness,  their 
aleontology,  and  especially  the  geological  history,  for  elevating  each  to  the 
ank  of  a  system  as  is  done  in  this  report.  The  most  important  reason  for 
his  treatment  is  the  fact  that  hundreds  of  thousands  if  not  millions  of  years 
lapsed  between  the  formation  of  the  highest  Mississippian  rocks  of  most  of 
he  eastern  United  States,  and  the  deposition  of  the  lowest  Pennsylvanian. 
)uring  this  interval  there  was  a  great  continental  revolution.  The  greater 
>art  of  the  eastern  United  States  was  elevated  above  the  level  of  the  sea  in 
diich  most  of  the  Mississippian  rocks  had  been  laid  down,  and  dry  land  con- 
itions  existed  where  formerly  the  sea  had  prevailed.  After  a  very  long  time 
he  land  was  worn  down  nearly  to  sea  level  and  the  Pennsylvanian  or  "Coal 
Measures"  rocks  began  to  be  deposited.  Such  great  changes  in  the  earth's 
istory  are  considered  as  dividing  lines  between  periods,  just  as  great  changes 
q  human  history  serve  to  divide  it  into  periods  and  epochs.  Further  discus- 
ion  of  this  subject  is  given  on  later  pages. 

The  Mississippian  system  has  been  named  from  the  Mississippi  Valley 
/here  it  is  typically  developed.  The  rocks  of  the  system  in  this  typical  region 
all  naturally  into  a  lower  and  an  upper  division.  The  lower  division  is  made 
ip  predominantly  of  limestones  with  some  shales  and  a  very  minor  amount 
f  sandstone;  the  upper  Mississippian  of  the  same  region  is  much  more  hetero- 
;enous  in  its  composition,  limestones  are  much  less  conspicuous  than  in  the 
ower  division,  those  that  are  present  are  commonly  much  more  shaly  in 
haracter,  and  there  are  important  sandstone  formations  included  in  the  series, 
throughout  the  entire  Mississippian  the  limestones  are  highly  fossiliferous, 
'eing  filled  in  many  places  with  a  great  variety  of  fossil  remains  of  many 
ifferent  kinds  of  marine  animals. 

The  present  chapter  will  be  devoted  to  a  consideration  of  the  Lower 
■lississippian  formations,  the  following  of  which  are  recognized  in  Hardin 
bounty,  from  the  lowest  to  the  highest :  Osage  formation,  Warsaw  limestone, 
\t.  Louis  limestone,  and  Ste.  Genevieve  limestone. 

91 


92  geology  of  hardin  county 

Osage  Formation 
name  and  distribution 

The  Osage  formation  is  widely  distributed  through  the  Mississippi  Valley, 
where  it  is  divisible  into  several  members.  In  southeastern  Iowa  it  is  repre- 
sented by  the  Burlington  and  Keokuk  limestones,  and  the  same  members  can 
be  more  or  less  distinctly  recognized  in  a  southerly  direction  in  Mississippi 
River  sections,  and  in  the  sections  which  encircle  the  Ozark  region  of  southern 
Missouri.  In  northwestern  Arkansas  and  adjacent  portions  of  Oklahoma  and 
Missouri  the  beds  representing  the  formation  have  commonly  been  designated 
as  the  Boone  chert,  named  from  the  exposures  in  Boone  County,  Arkansas.1 
In  southeastern  Missouri  and  in  the  adjacent  part  of  Illinois  a  basal  member 
of  the  formation  has  been  called  the  Fern  Glen  limestone2,  and  the  same  mem- 
ber extends  into  northern  Arkansas  where  it  constitutes  a  part,  at  least,  of  the 
beds  that  have  been  called  St.  Joe  marble  by  the  Arkansas  Geological  Survey.3 
To  the  eastward  the  Osage  is  represented  by  the  "Waverly  group"  of  Ohio, 
and  by  the  aKnobstone"  of  Indiana.  In  Tennessee  and  Alabama,  beds  of  the 
same  age  have  been  called  the  Fort  Payne  chert  by  Hayes4  and  others.  In 
Hardin  County,  Illinois,  and  in  Kentucky,  strata  of  Osage  age  were  called  the 
Tullahoma  formation  by  Ulrich3  and  by  Bain0,  although  that  name  had  been 
used  some  years  ealier  by  Safford7  in  Tennessee.  In  Hardin  County,  Bain 
used  the  name  Tullahoma  to  include  all  the  beds  between  the  black  shale  and 
the  St.  Louis  limestone,  including,  therefore,  the  beds  referred  to  the  Warsaw 
in  this  report;  but  as  originally  applied  by  Safforcl  in  Tennessee  it  is  uncertain: 
whether  the  Tullahoma  includes  beds  of  Warsaw  age. 

In  the  older  literature  of  Iowa,  Illinois,  and  Missouri,  the  names  Bur- 
lington and  Keokuk  limestones  were  used  almost  exclusively  for  these  beds, 
and  in  most  of  the  area  of  outcrop  in  these  states  these  two  members  can  be 
readily  distinguished.  As  observations  were  extended,  however,  it  was  found 
to  be  difficult  to  establish  with  certainty  in  all  sections  the  line  of  demarcation 
between  these  two  limestones,  and  because  of  this  Williams8  proposed  the  name 
Osage  for  the  larger  unit  which  should  combine  the  Burlington  and  Keokuk 
limestones  and  their  equivalents  throughout  the  Mississippi  Valley.  The  name 
Osage  was  derived  from  Osage  River  in  Missouri.  Keyes,  likewise,  in  his  lowaj 
work,  recognized  the  desirability  of  uniting  these  two  limestones,  and  used 
the  name  Augusta9  with  the  same  significance  as  Osage.  The  names  Boone, 
Tullahoma,   and   Fort   Payne   were  all   proposed   originally   as   strictly  local  I 

1  Simonds,  Ark.   Geol.  Surv.,   Ann.  Rep.   1888.  vol.   4,  p.   27    (1891). 
2Weller,   Trans.   Acad.   Sci.    St.   Louis,   vol.   16,   p.   438    (1906). 

3  Hopkins,  Ark.  Geol.   Surv.,  Ann.   Rep.   1890,  vol.  4,  p.   253    (1893). 

4  Bull.  Geol.   Soc.  Amer.,  vol.   2,  p.   143    (1890). 

5  IT.  S.  Geol.  Surv.,  Prof.  Paper  30,  p.   26    (1905). 
CU.  S.  Geol.  Surv.,  Bull.  255,  p.  19   (1905). 

7  Elements  of  Geol.  of  Tenn.,  p.  143  (1900). 
8U.  S.  Geol.  Surv.,  Bull.  80,  p.  169  (1891). 
9  la.  Geol.  Surv.,  vol.  1,  p.  59    (1893). 


LOWER   MISSISSIPPIAN  93 

)rmation  names  without  any  adequate  understanding  of  the  broad  correlation 
f  the  strata,  while  Osage  was  proposed  as  a  comprehensive  stratigraphic  unit 
aving  a  definite  position  in  the  Mississippian  section  of  the  Mississippi  Valley 
>gion,  and  consequently  it  is  adopted  here  for  use  in  Hardin  County. 

In  Hardin  County  the  Osage  formation  outcrops  only  in  an  oval  belt  of 
mntry,  from  one-half  to  over  one  mile  wide,  encircling  the  area  of  the 
•evonian  limestone  and  the  belt  of  Chattanooga  shale  of  the  Hicks  dome.  The 
>wn  of  Hicks  is  located  upon  the  outcrop  of  the  formation.  The  chert  of 
le  Osage  is  more  resistant  to  decay  and  removal  than  the  strata  on  each  side ; 
msequently  its  outcrop  forms  a  broad  ridge  which  incloses  the  valleys  in 
hich  the  outcrops  of  the  Chattanooga  shale  are  situated.  The  strata  of  the 
sage  ridge  dip  away  from  the  Hicks  dome  in  every  direction  at  angles  of 
■om  10°  to  20°.  This  ridge  is  deeply  covered  with  chert  debris  made  up  of 
i-agments  generally  less  than  six  inches  in  diameter.  The  principle  exposure 
f  the  Osage  in  place  in  Hardin  County,  is  along  the  bed  of  Hicks  Branch  in 
le  southwestern  part  of  sec.  25,  T.  12  S.,  E.  7  E.,  where  the  stream  has 
oded  a  deep  valley  through  the  ridge.  Along  the  bed  of  this  stream  there  is 
nearly  continuous  exposure  of  the  formation  from  top  to  bottom.  The  bed 
'Ck  of  the  Osage  is  exposed  at  only  two  other  points  in  Hardin  County,  and 
t  each  of  these  only  a  few  feet  can  be  seen. 

LITHOLOGIC    CHARACTER 

The  Osage  formation,  so  far  as  it  is  exposed  to  examination  in  Hardin 
bunty,  is  almost  exclusively  a  chert  bedded  in  layers  up  to  one  foot  thick, 
he  only  exception  to  this  condition  that  has  been  observed,  is  on  Goose  Creek 
;  sec.  32,  T.  12  S.,  E.  8  E.,  about  one-fifth  mile  east  of  the  west  line  of  the 
etion,  where  a  few  feet  of  black  limestone  is  exposed,  passing  into  chert  as 
|e  beds  extend  upward  into  the  creek  bank.  As  exposed  in  Hicks  Branch 
e  chert  is  apparently  a  siliceous  replacement  of  evenly  bedded  limestone, 
he  chert  fragments  as  they  occur  strewn  over  the  surface  of  the  ground  have 
me  distinctive  characters,  generally  being  grayish,  yellowish,  or  bluish  in 
lor.  Much  of  the  chert  is  in  elongated  fragments  with  rudely  triangular 
oss  sections,  and  with  smooth  lateral  faces.  Much  of  it  is  also  finely  color- 
.nded  in  gray,  pink,  or  yellow,  the  bands  being  either  concentric,  as  in  some 

the  loose  pieces,  or  parallel  with  the  bedding,  as  in  the  chert  layers  in  place. 

texture  the  chert  ranges  from  compact,  brittle,  or  tough,  through  somewhat 
tous  and  tough  to  finely  porous  and  somewhat  friable.  Some  of  the  hard, 
nse  chert  seems  to  be  minutely  cracked  so  that  it  may  be  shattered  easily 
to  small  angular  fragments.  A  notable  characteristic  of  these  Mississippian 
erts  is  the  almost  total  absence  of  fossils,  which  is  a  great  contrast  to  the 
ert  of  similar  age  elsewhere  in  the  Mississippi  Valley  region  where  much 

it  is  crowded  with  crinoid  plates  and  other  fossils.   .  Isolated  stem  plates 


94  GEOLOGY  OF  HARDIN  COUNTY 

of  crinoids  have  been  observed  rarely  in  Hardin  County,  and  a  very  few  other 
fossils,  but  most  of  the  chert  is  entirely  without  fossils  of  any  sort.  The  finely 
porous,  more  friable  chert  resembles  a  fine-grained  sandstone  and  may  have 
been  originally  a  siliceous  limestone  in  which  the  silica  occurred  in  the  form 
of  very  fine  quartz  grains. 

Although  the  Osage  manifests  itself  on  the  surface  as  chert,  this  chert  is 
quite  likely  only  a  superficial  development,  and  the  formation  is  probably  a 
true  limestone  below  the  depths  to  which  water  and  air  have  had  free  access 
and  circulation — in  other  words,  below  the  zone  of  active  weathering.  Such 
superficial  change  of  limestone  to  chert,  by  the  solution  of  the  carbonate  of 
lime  and  the  deposition  of  silica  in  its  place,  is  a  common  process  in  nature. 
The  only  direct  evidence,  however,  that  the  Osage  is  essentially  limestone  in 
its  original  condition,  is  the  outcrop  of  fine-grained  black  limestone  about  ten 
feet  thick,  in  the  bank  of  Goose  Creek,  which  has  been  described  above.  At 
this  locality  the  change  from  the  limestone  to  chert  upward  from  the  chert 
bed,  is  exhibited.  It  is  probable  that  a  boring  through  the  Osage  where  it  is 
500  feet  below  the  surface  would  show  little  but  limestone.  There  is  no  evi- 
dence of  any  shale  in  the  formation  as  was  asserted  by  Bain.1 

THICKNESS 

The  only  locality  in  the  county  where  an  estimate  of  the  thickness  of  the 
Osage  can  be  made,  is  on  Hicks  Branch,  at  the  locality  described  on  an  earlier 
page,  where  the  formation  is  so  well  exposed.  At  this  place  only  the  edges  of 
the  strata  are  shown  in  the  creek  bed,  so  that  the  thickness  cannot  be  measured 
directly,  but  must  be  calculated  from  the  width  of  the  outcrop  and  the  average 
angle  of  dip.  The  width  of  ,the  outcrop  at  this  locality  is  2,000  feet,  and  th( 
average  dip  is  16°  SW.,  computed  from  17  independent  measurements  well 
distributed  across  the  outcrop,  which  makes  the  thickness  550  feet,  this  being 
the  best  estimate  that  can  be  made  under  the  conditions,  and  being  nearly 
three  times  as  great  as  that  recorded  by  Bain.2 

PALEONTOLOGY 

As  already  stated,  the  Osage  in  Hardin  County  is  nearly  unfossiliferous, 
in  this  respect  being  in  great  contrast  to  its  character  in  the  Mississippi  Valley 
and  in  Alabama  and  eastern  Tennessee.  The  Hardin  County  locality  occupies 
a  position  between  the  other  two  regions  mentioned,  and  it  is  a  remarkable 
circumstance  that  in  this  intermediate  region  fossils  should  be  so  scarce.  A 
possible  explanation  of  the  fact  may  be  that  the  crinoids,  bryozoa,  and 
brachiopods,  so  abundant  in  the  Osage  and  its  equivalents  elsewhere,  were 
especially  adapted  to  life  in  shallow,  warm  water,  such  as  doubtless  existed 

'U.  S.  Geol.  Surv.,  Bull.   255,  p.  19    (1905). 
2  Loc.   cit.,  p.   19. 


LOWER    MISSISSIPPIAN  95 

generally  throughout  the  Osage  sea.  The  Hardin  County  area  may  have  been 
a  deeper  depression  of  the  sea  floor  where  the  water  was  too  deep  for  the 
animals  to  live  upon  the  bottom,  and  into  which  their  hard  parts  were  not 
washed  by  currents  from  shallow  water.  The  few  fossils  that  have  been  col- 
lected from  the  formation,  as  the  result  of  constant  vigilance  and  persistent 
search  are  listed  below : 

List  of  fossils  from  the  Osage  formation 

Productus   burlingtonensis  Hall?  Solenomya  ?  sp. 

Productus  setigera  Hall  Sphenotus  ?  sp. 

Rhynchopora  ?  sp.  Phanerotrema  ?  sp. 

Aviculopecten   sp.  Griffithides  sp. 
Posidonomya  ?  sp. 

Most  of  the  material,  as  appears  from  the  list,  is  too  poorly  preserved  and 
too  scanty  for  even  certain  generic  identification,  although  there  is  probably 
but  little  ground  for  doubt  on  that  point.  There  is  nothing  especially  signi- 
ficant for  stratigraphic  determination  in  the  list.  All  the  genera  are  known 
to  occur  in  the  Osage,  and  most  of  them  have  a  longer  range,  but  none  of  the 
forms  recorded  throw  any  light  upon  the  depth  of  the  water  or  other  conditions 
in  the  region  during  Osage  time. 

CORRELATION 

Because  of  the  scarcity  of  fossils  the  identification  of  the  Hardin  County 
rocks  in  question  as  Osage,  must  rest  mainly  upon  their  stratigraphic  rela- 

i  tions.    They  occupy  the  same  position  between  the  Chattanooga  shale  and  the 

;  Warsaw  limestone,  as  do  the  Burlington  and  Keokuk  limestones  of  the  Mis- 
sissippi Valley;  also  the  same  position  above  the  Chattanooga  shale  as  the 
Fort  Payne  in  eastern  Tennessee  and  Alabama.  Moreover,  by  its  fossils  in 
Tennessee  and  Alabama,  the  Fort  Payne  is  to  be  correlated  with  the  Keokuk 

;  at  least,  and  it  possibly  includes  beds  equivalent  to  all  or  some  part  of  the 
Burlington  limestones,  as  does  the  Tullahoma  formation  in  central  Tennes- 

I  see.     On  general  grounds,  therefore,  there  seems  to  be  no  reason  to  doubt  the 

!  correctness  of  the  correlation  of  the  Hardin  County  chert  formation  with  the 
Fort  Payne  to  the  east  and  the  Keokuk-Burlington  to  the  west.  Its  thick- 
ness is  much  greater  than  that  of  the  Fort  Payne,  and  is  about  "that  of  the 
Osage  group   of  southern  Indiana   and  the  Louisville  region  of  Kentucky, 

1  where  it  is  composed  of  the  New  Providence  shale  below,  the  Kenwood  sand- 
stone in  the  middle,  and  the  Rosewood  shale  and  Holtsclaw  sandstone  above, 
aggregating  600  feet.  On  the  other  hand  the  Osage  of  Hardin  County  is 
much   thicker  than   the   Keokuk   and   Burlington  limestones   of  the   Missis- 

j  sippi  Valley,  which  have  a  maximum  combined  thickness  of  only  225  feet. 
From  these  circumstances  it  appears  reasonable  to  suppose  that  the  Osage 
of  this  region  includes  the  equivalents  of  both  the  Keokuk  and  the  Burlington. 


96  GEOLOGY  OF  HARDIN  COUNTY 

However,  there  is  one  item  of  evidence  tending  to  show  that  the  Osage  of 
Hardin  County  includes  only  beds  of  Keokuk  age  and  is  nearly  equivalent 
to  the  Fort  Payne  chert.  Seven  miles  north  of  Hardin  County  and  just  west 
of  the  Saline-Gallatin  county  line,  near  the  north  entrance  to  Horseshoe 
Gap  three  miles  southwest  of  Equality,  the  Osage  outcrops  on  a  conspicuous 
knoll  and  is  the  same  in  character  and  thickness  as  in  Hardin  County. 
Below  the  Osage  at  this  locality  the  Chattanooga  shale  also  outcrops  as  re- 
vealed by  fragments  of  the  characteristic,  black,  fissile  shale;  but  between 
the  Chattanooga  and  the  Osage  is  a  few  feet  of  dark,  irregularly  fissile  shale 
with  peculiar  curly  markings  like  worm  trails.  Now  these  peculiar  markings 
are  characteristic  of  the  Eosewood  shale  of  the  Louisville  region,  Kentucky, 
of  determined  Keokuk  age.  They  are  widely  distributed  throughout  all  the 
region  from  Crawfordsville,  Indiana,  to  Overton  and  Davidson  counties, 
Tennessee,  where  they  invariably  occur  in  shale  which  is  everywhere,  by  all 
criteria,  to  be  correlated  with  the  Rosewood.  In  other  words,  such  evidence 
as  is  known  indicates  that  the  Osage  chert  at  the  locality  described  above,  has 
beneath  it  shale  of  Keokuk  age  and  therefore  includes  no  component  of  Bur- 
lington age,  and  the  condition  in  Hardin  County  would  presumably  be  the 
same. 

Meramec  Group 

By   Stuart  Weller 

As  originally  defined,  the  Meramec  group1  included  in  ascending  order, 
the  Warsaw  limestone,  the  Spergen  (Salem)  limestone,  and  the  St.  Louis 
limestone.  In  the  present  report  the  Ste.  Genevieve  limestone  is  also  included 
as  a  fourth  formation  in  the  group,  above  the  St.  Louis  limestone.  For 
many  years  after  the  original  definition  of  the  Ste.  Genevieve  limestone  by 
Shumard  in  1859,  the  formation  was  scarcely  or  not  at  all  recognized,  the 
beds  representing  it  being  commonly  included  with  the  St.  Louis  limestone. 
LTlrich  revived  the  name  of  the  formation  in  1905,  but  excluded  it  from  the 
Meramec  group,  making  it  the  lowest  formation  of  the  Chester  group,  an 
interpretation  that  he  still  holds  to  at  this  time.  All  the  evidence,  however, 
that  has  been  gathered  during  a  period  of  a  dozen  years,  shows  the  much 
closer  relationship  of  the  Ste.  Genevieve  to  the  St.  Louis  limestone  than  to 
any  of  the  Chester  formations.  In  a  number  of  publications  during  recent 
years,  as  a  compromise  measure,  the  Ste.  Genevieve  has  been  treated  as  a 
separate  unit  in  the  Mississippian  system,  being  united  with  neither  the 
Meramec  group  below,  nor  the  Chester  group  above,  but  the  time  has  now 
come  when  it  is  desirable  to  place  the  Ste.  Genevieve  limestone  where  it 
properly  belongs,  with  the  St.  Louis  limestone.     In  order  to  accomplish  this 

iUlrich,   U.    S.   Geol.    Surv.,   Prof.   Paper  No.    24,    table   opposite   p.    90    (1904);    also, 
U.  S.  Geol.  Surv.,  Prof.  Paper  No.  36,  p.  28    (1905). 


LOWER   MISSISSIPPIAN  97 

result  it  is  necessary  either  to  modify  the  original  definition  of  the  Meramec 
group  so  that  it  shall  include  the  Ste.  Genevieve  limestone,  or  to  propose  a 
new  group  name  for  the  four  formations.  As  it  seems  more  desirable  to 
retain  the  name  already  in  use  with  a  slightly  modified  definition,  than  to 
add  confusion  to  the  nomenclature  by  introducing  a  totally  new  name,  such 
a  procedure  is  consequently  followed  here. 

Warsaw  Limestone 

name  and  distribution 

Throughout  the  Mississippi  Valley,  wherever  the  Osage  is  present,  it  is 
succeeded  by  the  Warsaw  formation.  The  formation  is  also  present  in  south- 
western Indiana  and  southward  into  Kentucky,  where  it  has  been  called  the 
Harrodsburg  limestone,  and  extends  southward  through  Kentucky  and  Ten- 

i  nessee  and  probably  into  northern  Alabama.  The  name  of  the  formation  is 
derived  from  the  town  of  Warsaw  in  western  Illinois,  situated  on  Missis- 
sippi Eiver  nearly  opposite  Keokuk,  Iowa.  As  originally  used  the  name  was 
applied  only  to  beds  which  overlie  the  so-called  "geode  beds"  of  the  section 
at  Keokuk  and  Warsaw,  these  lower  beds  being  included  in  the  Keokuk 
formation.  More  recent  studies  have  shown  that  the  true  line  of  demarcation 
between  the  Keokuk  and  Warsaw  is  more  properly  at  the  base  of  the  "geode 

.bed"  instead  of  at  the  summit  of  it,  and  such  an  emended  definition  of  the 

Warsaw  formation  has  been  accepted  by  the  United  States  Geological  Survey. 

In  Hardin  County  the  Warsaw  comes  to  the  surface  only  in  an  oval 

belt  encircling  the  Hicks  dome,  and  varying  in  width  from  one-fourth  of  a 

| mile  to  one  mile.  One  extremity  of  this  belt,  along  its  longer  axis,  lies  just 
northwest  of  Hicks.  The  opposite  extremity  crosses  Goose  Creek  at  Wolrab 
Mill.  It  lies  along  and  east  of  Big  Creek  in  sees.  28  and  33,  T.  12  S.,  K.  8 
E.,  and  passes  diagonally  through  sec.  36  and  across  the  southwest  corner  of 
sec.  26,  T.  12  S.,  E.  7  E.  The  Warsaw  in  this  region  is  denned  as  including 
all  the  beds  lying  between  the  continuous,  non-fossiliferous  chert  of  the  Osage 
below,  and  the  lowest  limestone  beds  carrying  the  fossil  coral  Lithostrotion 
above,  the  beds  with  Lttliostrotion  being  assigned  to  the  St.  Louis  limestone. 
Ordinarily  the  bounds  between  the  Warsaw  and  Osage  can  not  be  determined 
with  certainty.  On  Hicks  Branch  in  the  southwest  quarter  of  sec.  25  the 
boundary  is  placed  between  the  continuous  chert  mass  of  the  Osage  below 
and  the  almost  continuous  limestone  mass,  regarded  as  Warsaw,  above.  There 
are  no  exposures  at  or  near  this  contact  elsewhere  in  the  county,  and  the 
position  of  the  boundary  has  been  roughly  approximated  in  the  mapping  of 

;the  formation;  but  it  is  reasonably  certain,  from  fossil  evidence,  that  the 

^boundaries  as  located  are  correct  to  within  narrow  limits. 
—7  G 


98  GEOLOGY    OF    HARDIN    COUNTY 

LITHOLOGIC    CHARACTER 

Approximately   the   lower   three-fourths   of   the   Warsaw   formation,    as 
exposed  on  Hicks  Branch  in  the  SW.  %  sec.  25,  T.  12  S„  B.  7  E,  is  a  dark 
to  black,  fine-grained,  somewhat  cherty  and  sparingly  fossiliferous  limestone. 
The  upper  one-fourth  contains  a  considerable  proportion  of  coarse-grained, 
light-gray  limestone  in  thick  layers,  intercalated   with  which  are  layers  of 
shale  and  layers  of  dark,  shaly-weathering  limestone.     Much  of  the  lower 
main  body  of  the  Warsaw  is  well  exposed  in  the  Hicks  Branch  locality  just 
mentioned.     The  limestone  layers  are  commonly  a  foot  or  two  in  thickness, 
the  rock  is  mostly  dark  to  black,  fine-grained,  and  includes  a  considerable 
amount  of  chert  in  rough,  irregularly-sprawling,  flatfish  masses.     This  part 
of  the  Warsaw  is  hardly  different  lithologically  from  much  of  the  overlying 
St.   Louis  limestone.     On  long-continued  weathering  near  the  surface  it  is 
largely  silicified  to  brittle,  fossiliferous  chert,  a  good  exhibition  of  which  is 
present  in  the  road  ditch  just  north  of  Hicks.    This  chert  can  be  distinguished 
from   the    similarly   bedded    Osage    chert   by    its   fossils,    which    are    fairly 
numerous,  while  the  Osage  chert  is  essentially  non-fossiliferous. 

The  uppermost  fourth  of  the  Warsaw  differs  from  the  lower  part  of  the 
formation  in  the  presence  of  thick-bedded,  coarsely  granular,  predominantly 
light-gray  limestone,  but  with  some  dark  gray  layers,  some  dark,  fine-grained 
to  almost  non-granular  layers  having  a  conchoidal  fracture,  and  thick  black 
layers  weathering  to  thin  laminae.  The  general  character  of  this  part  of 
the  Warsaw  is  exhibited  in  an  exposure  on  the  bank  of  Big  Creek  in  the 
northern  part  of  sec.  33,  T.  12  S.,  B.  8  E.  At  this  locality  the  following 
succession  of  beds  is  exhibited: 

Section  of  part  of  the  upper  Warsaw  beds  on  Big  Creek  in  the  northern  part  of 

sec.  S3,  T.  12  8.,  R.  8  E. 

Feet 

Limestone,  dark  gray,  coarse-grained   (crinoidal) 

Limestone,  thick-bedded,  weathering  shaly 

Limestone,  light-gray,  coarse-grained    (crinoidal) 

Limestone,  dark,  thick-bedded,  weathers  shaly,  Bryozoa  plentiful 3j 

40 

An  exposure  of  about  40  feet  of  limestone  at  this  horizon  is  present  on 
the  southern  point  of  the  spur  in  the  SW.  l/4  sec.  5,  T.  12  S.,  R.  8  E.,  where 
the  road  crosses  on  the  line  between  sees.  5  and  8.  It  is  mainly  dark-gray, 
and  coarse-grained,  but  the  dark,  non-granular  limestone  is  also  present.  The 
limestone  exposures  of  this  part  of  the  Warsaw  are  commonly  of  the  light- 
gray,  coarse-grained  sort.  The  rock  is  highly  fossiliferous  and  its  granular 
character  is  largely  due  to  the  abundance  of  crinoidal  plates  and  to  fragments 


LOWEK    MISSISSIPPIAN 


99 


of  other  fossils  which  have  been  altered  to  crystalline  calcite.  Layers  of  this 
coarse,  light-gray,  crinoidal  limestone  are  well  exposed  in  the  road  ditch  at 
Wolrab  Mill.  The  weathered  surface  is  very  rough  by  reason  of  the  pro- 
jecting fragments  of  fossils,  mostly  more  or  less  broken  crinoid  plates,  and 
shells  of  various  sorts.  Much  of  the  limestone,  on  extreme  weathering,  has 
become  altered  to  a  coarsely  porous,  reddish  chert  resembling  a  red  rubber 
sponge.  Dense,  platy,  fossiliferous,  gray  chert  also  occurs,  and  is  especially 
abundant  on  the  long,  low  spurs  in  the  southwest  corner  of  sec.  5,  T.  12  S., 
E.  8  E.,  and  on  the  slope  above  the  road  in  the  extreme  southwest  corner  of 
sec.  33,  T.  12  S.,  B.  8  E.,  about  one-fourth  of  a  mile  northeast  of  Wolrab 
Mill.  In  some  situations,  where  not;  silicified,  these  coarse-grained  layers 
form,  on  weathering,  a  white,  chalky  crust  as  much  as  one-eighth  of  an  inch 
thick. 

THICKNESS 

As  deduced  from  the  dip  and  width  of  outcrop  on  Hicks  Branch  in  the 
SW.  %  sec.  25,  T.  12  S.,  E.  7  E.,  the  Warsaw  is  250  feet  thick. 

PALEONTOLOGY 

Fossils  are  fairly  abundant  in  the  Warsaw,  although  they  are:  not  as  a 
rule  well  preserved,  and  good  specimens  are  not  common.  Most  of  them  occur 
in  the  upper  fourth  of  the  formation  which  is  characterized  by  the  coarse- 
grained, light-gray  limestone,  but  in  addition  to  these  much  of  the  limestone 
throughout  the  formation  is  crowded  with  fenestellid  bryozoans.  The  fossils 
are  developed  from  their  original  limestone  matrix  and  revealed  to  view  only 
in  the  chert.    A  list  of  the  species  that  have  been  identified  is  as  follows : 


List  of  fossils  from  the  Warsaw  limestone 


Triplophyllum,  a  small  slender 
species;    common 

Pentremites   conoideus   Hall 

Platycrinus,  rather  large  species  with 
oval,  spiny  stem  plates  one-half 
inch  in  diameter  or  larger;  com- 
mon; entire  bases  indicating  heads 
y2  to  1  inch  in  diameter  occasion- 
ally found 

Cystodictya  lineata  Ulrich 

Cystodictya  pustulosa   Ulrich 

Dichotrypa  sp. 

Fenestella  tenax  Ulrich 

Hemitrypa  proutana  Ulrich 


Lyropora  sp. 

Polypora  simulatrix  Ulrich 

Athyris  densa  Hall;    common 

Brachythyris   suborbicularis    (Hall)? 

Brachythyris  subcardiiformis  (Hall)? 

Camarotoechia   mutata    (Hall)? 

Cleiothyridina   hirsuta    (Hall) 

Eumetria  verneuiliana    (Hall) 

Rhipidomella  dubia    (Hall) 

Spirifer  bifurcatus  Hall 

Spirifer   lateralis   Hall 

Spirifer  subequalis  Hall 

Spirifer  tenuicostatus  Hall;    common 

Spiriferina  subtexta  White? 


100  GEOLOGY    OF    HABDIN    COUNTY 


CORRELATION 


Several  of  the  species  recorded  in  the  foregoing  list  are  known  elsewhere 
only  from  the  Warsaw  and  Spergen  limestones.  Snch  are  Pentremites 
conoideus,  Athyris  densa,  Brachythyris  subcardiiformis,  and  Spirifer  lateralis. 
Athyris  densa  has  been  recorded  as  a  Spergen  limestone  fossil  but  the  original 
specimens  were  collected  in  Indiana  and  Kentucky  from  beds  that  are  now 
known  to  be  Harrodsburg  limestone,  of  Warsaw  age,  and  there  is  no  authentic 
record  of  its  occurrence  in  the  Spergen,  or  in  any  horizon  other  than  the 
Harrodsburg  limestone  or  its  equivalents.  Spirifer  lateralis  and  Spirifer  sub- 
equalis  are  not  known  below  the  Warsaw,  nor  are  they  reported  from  above 
the  Spergen.  Poly  pom  simulatrix  is  reported  from  the  Keokuk  and  Warsaw 
but  not  from  higher  beds.  Altogether  the  assemblage  seems  to  be  character- 
istic of  the  Warsaw  and  justifies  the  classification  here  made.  It  is  possible 
that  the  upper  fourth  of  the  250  feet  of  limestone  here  classed  as  Warsaw — 
the  part  with  the  coarse,  light-gray,  fossiliferous  layers — may  represent  the 
Spergen,  but  there  is  no  compelling  evidence  for  such  a  determination. 
Athyris  densa,  a  supposed  Spergen  species,  is  common  in  this  part  of  the 
Warsaw,  but  as  has  already  been  explained  the  species  is  actually  known 
elsewhere  only  in  the  Harrodsburg  limestone  of  Warsaw  age. 

St.  Louis  Limestone 

By  Stuart  Weller 
NAME  AND  DISTRIBUTION 

The  St.  Louis  limestone  has  received  its  name  from  St.  Louis,  Missouri, 
where  the  formation  is  typically  developed.  It  is  well  exposed  in  the  Missis- 
sippi River  bluffs  and  in  quarries  in  that  city,  and  extensive  exposures  are 
present  above  and  below  the  city  upon  both  the  Missouri  and  Illinois  sides 
of  the  river.  The  formation  is  recognized  as  far  north  as  southeastern  Iowa, 
and  southward  along  the  Mississippi  to  Ste.  Genevieve  County,  Missouri,  and 
still  further  south  in  Illinois.  Across  southern  Illinois  the  formation  out- 
crops at  intervals  from  Union  County  to  Hardin  County,  and  continues  into 
Indiana,  and  southward  into  Kentucky  and  Tennessee.  The  same  formation 
extends  to  Alabama  and  to  other  localities  in  the  Appalachians  north  of 
Alabama.  Throughout  this  entire  area  the  St.  Louis  limestone  originally 
existed  as  a  continuous,  blanket-like  formation,  and  was  deposited  as  a  mass 
of  calcareous  sediment  in  the  bottom  of  a  sea  which  covered  the  area,  and 
which  doubtless  spread  beyond  the  limits  of  the  formation  as  now  exposed. 
The  formation  is  not  continuously  present  at  the  surface  throughout  this 
area.  In  the  larger  part  of  the  region  it  is  covered  by  younger  formations, 
and  its  presence  could  only  be  detected  by  deep  excavations  or  by  deep 
drilling.     Elsewhere  within  the   specified  area,  rock  formations  older  than 


LOWER    M1SSISSIPPIAN 


101 


the  St.  Louis  limestone  are  exposed  at  the  surface,  and  in  such  situations 
the  St.  Louis  formation  which  was  originally  present,  has  been  removed 
through  the  process  of  erosion. 

In  Hardin  County  the  St.  Louis  limestone  occurs  in  each  of  the  three 
structural  areas.  In  the  southeastern,  non-faulted  portion  of  the  county,  the 
formation  occupies  a  considerable  area  between  Elizabethtown  and  Cave  in 
Rock.    Between  these  two  points  it  is  well  exposed  in  the  Ohio  Eiver  bluffs. 


Fig.  4. — Bluff  of  St.  Louis  limestone  at  Tower  Rock,  midway  between  Elizabethtown 

and  Cave  in  Rock. 


and  extends  northward  from  the  river  bank  for  an  extreme  distance  of  about 
two  miles.  Farther  to  the  north  the  formation  continues  beneath  the  Ste. 
Genevieve  limestone,  so  that  the  northern  limit  of  the  area  of  its  outcrop  is 
the  sinuous  line  representing  the  intersection  between  the  St.  Louis-Ste. 
Genevieve  contact  surface  and  the  irregular  topographic  surface.  The  loca- 
tion of  this  line  upon  the  map  is  liable  to  some  error  because  of  the  difficulty 


102  GEOLOGY    OF    HARDIN    COUNTY 

of  determining  just  where  the  line  between  these  two  formations  should  be 
placed,  and  because  of  the  covering  of  surficial  material  which  so  effectually 
obscures  the  rock  outcrops  over  much  of  the  area. 

In  the  central,  much-faulted  belt  of  the  county,  the  St.  Louis  limestone 
outcrops  in  two  distinct  areas,  both  of  them  in  the  northwestern,  less  depressed 
segment  of  the  belt  (see  figure  3).  One  of  these  is  situated  along  the  valley 
of  Hogthief  Creek,  extending  nearly  two  miles  northeast  of  Jacksons  Store 
and  about  one  and  one-half  miles  southwest  of  the  same  point.  The  extreme 
width  of  the  area  does  not  exceed  one  mile.  On  the  southeast  it  is  limited  by 
one  of  the  long  northeast-southwest  faults  of  the  belt,  being  adjacent  to  the 
Pottsville  and  higher  Chester  formations.  The  northwestern  border  of  the 
area  is  a  sinuous  line  of  normal  contact  with  the  overlying  Ste.  Genevieve 
limestone.  The  second  area  of  St.  Louis  limestone  within  the  faulted  belt  is 
in  the  valley  of  Big  Creek,  above  and  below  Illinois  Furnace,  and  in  some 
of  its  tributaries  from  the  west.  It  is  limited  both  to  the  northwest  and 
to  the  southeast  by  faults.  The  extreme  length  of  the  area  is  approximately 
five  miles  in  a  northeast-southwest  direction,  southwest  from  a  point  about 
one  mile  northeast  of  Illinois  Furnace.  The  width  of  the  area  increases 
from  about  one  mile  at  its  northernmost  extremity  to  nearly  one  and  one-half 
mile  at  the  south. 

In  the  northwestern  part  of  the 'county  the  St.  Louis  limestone  occupies 
an  incomplete  belt  about  the  Hicks  dome,  the  width  of  the  belt  being  approx- 
imately one-half  mile.  To  the  southeast  the  continuity  of  the  belt  is  destroyed 
by  the  Wolrab  Mill  fault,  so  that  the  area  of  outcrop  is  U-shaped  rather  than 
elliptical,  which  is  the  outline  of  the  outcropping  belts  of  the  next  three  under- 
lying formations. 

LITHOLOGIC    CHARACTER 

In  its  general  characters  the  lithologic  features  of  the  St.  Louis  lime- 
stone are  similar  throughout  the  entire  area  of  its  distribution.  In  Hardin 
County,  where  it  is  not  notably  different  from  other  localities,  the  upper  75 
to  100  feet  is  in  the  main  gray,  bluish-gray,  or  blue,  while  a  large  part  bf 
the  lower  250  to  300  feet  is  dark  or  nearly  black  limestone.  For  the  most 
part  it  has  been  deposited  in  even  beds  varying  in  thickness  from  a  few 
inches  to  several  feet.  In  the  river  sections  half  a  mile  west  of  Cave  in  Bock, 
the  bluish-gray  layers  constitute  the  upper  75  feet.  The  200  feet  below, 
exposed  to  the  west  along  the  river  as  far  as  Tower  Rock,  midway  between 
Cave  in  Bock  and  Elizabethtown,  is  predominantly  dark  gray  or  black.  It  is 
predominantly  dense,  and  fine-grained  in  texture,  a  few  beds  being  nearly  as 
fine-grained  as  lithographic  stone.  Other  beds  are  more  granular  and  some 
are  coarsely  crystalline.  No  oolitic  beds  have  been  recognized  with  certainty 
in  the  St.  Louis  limestone  of  Hardin  County.  Most  of  the  beds  are  hard 
and  tough,  but  those  of  lithographic  texture  are  brittle  and  break  with  a 


LOWER    MISSISSIPPIAN 


103 


conchoidal  or  splintery  fracture.  Much  of  the  limestone  of  the  formation 
contains  considerable  amounts  of  chert,  occurring  commonly  as  lenticular  or 
irregular  masses  distributed  along  horizontal  lines  parallel  with  the  bedding 
planes.  The  chert  is  still  more  conspicuous  in  the  residual  deposits  remaining 
after  the  decomposition  of  the  limestone.  In  the  limestone  itself  the  chert 
is  more  abundant  near  the  surface,  and  is  clearly  of  secondar}^  origin  being 
formed  by  the  replacement  of  limestone  by  silica;  and  it  is  not  unlikely  that 
the  original  source  of  much  of  the  silica  has  been  the  unconsolidated  surficial 
deposits  through  which  the  ground  waters  have  percolated  before  coming  in 
contact  with  the  solid  limestone  beneath,  although  some  of  the  silica  may 
have  been  disseminated  originally  through  the  limestone. 


Fig. 


-Bluff  of  St.  Louis  limestone  two  miles  west  of  Cave  in  Rock. 


In  one  respect,  that  is  in  its  color,  the  St.  Louis  limestone  of  Hardin 
County  and  the  adjacent  area,  is  distinctly  different  from  the  exposures  of  the 
same  formation  in  the  counties  bordering  Mississippi  River.  In  the  region 
here  being  described  the  formation  is  in  general  darker  in  color  than  it  is 
farther  west,  the  dark  color  being  more  marked  in  the  lower  part  of  the 
formation,  where  most  of  the  beds  are  nearly  black.  In  places  these  dark 
beds  which  may  be  a  foot  more  or  less  in  thickness,  are  separated  by  thin, 
somewhat  shaly  layers,  and  the  upper  and  lower  parts  of  the  solid  layers 
themselves  cleave  easily  and  somewhat  irregularly  along  the  bedding  planes, 
the  mid-portions  of  the  layers  being  much  more  dense  and  compact. 


104  GEOLOGY  OF  HARDIN  COUNTY 


STKATIGRAPHIC  RELATIONS 


Sedimentation  was  apparently  continuous  from  the  subjacent  beds  into 
the  St.  Louis  limestone.  The  lithologic  change  is  gradual  with  no  sharply 
defined  line  of  demarcation,  but  rather  with  a  gradual  transition  from  the 
lower  sediments  to  the  higher,  so  that  the  lower  boundary  line  of  the  forma- 
tion has  been  drawn  in  a  somewhat  arbitrary  manner. 

The  line  between  the  St.  Louis  limestone  and  the  overlying  Ste.  Genevieve 
is  also  an  indefinite  boundary/  and  no  evidence  has  been  found  in  Hardin 
County  to  show  that  any  break  in  sedimentation  occurred  in  passing  from  the 
older  to  the  younger  formation.  There  is,  however,  a  distinct  unconformity 
between  these  two  formations  farther  west,  in  Ste.  Genevieve  County,  Missouri, 
on  the  flank  of  the  ancient  Ozark  land,  the  unconformity  representing  one 
of  the  many  uplifts  experienced  by  Ozarkia  in  Paleozoic  time. 

THICKNESS 

It  has  not  been  practicable  to  make  a  complete,  measured  section  of  the 
St.  Louis  limestone  anywhere  in  Hardin  County,  and  it  is  commonly  im- 
practicable to  recognize  the  exact  line  of  demarcation  between  the  formation 
and  either  the  Warsaw  below  or  the  Ste.  Genevieve  above.  Because  of  these 
circumstances  the  determination  of  the  thickness  of  the  St.  Louis  limestone 
can  only  be  an  approximation.  The  formation  must  include,  however,  about 
350  feet  of  strata.  This  thickness  is  approximately  that  which  is  exhibited 
around  St.  Louis,  Missouri,  where  the  formation  is  typically  developed,  but 
it  is  considerably  greater  than  the  thickness  in  Ste.  Genevieve  County, 
Missouri,  where  less  than  100  feet  is  usually  exhibited,  or  in  southeastern 
Indiana. 

PALEONTOLOGY 

Good  fossils  are  not  commonly  abundant  in  the  St.  Louis  limestone  in 
Hardin  County,  except  locally.  Crinoidal  fragments,  mostly  stem  segments, 
are  numerous,  being  most  conspicuous  in  the  cherts  of  the  formation  where 
their  presence  is  shown  by  the  cavities  from  which  the  fossils  themselves 
have  been  removed  by  solution.  In  the  silicification  of  these  limestones  the 
matrix  was  easily  replaced  while  the  crystalline  calcite  of  the  crinoid  frag- 
ments and  other  fossil  shells  was  not  acted  upon.  Later,  upon  weathering, 
these  crystalline  calcite  portions  of  the  rock  were  removed  by  solution,  leaving 
the  residual  cherts  more  or  less  porous.  In  places  some  layers  of  the  St. 
Louis  limestone  contain  an  abundance  of  bryozoans,  largely  fenestellid  forms, 
which  may  be  seen  in  section  upon  the  weathered  surfaces  of  some  of  the  hard 
limestone  layers,  but  no  shaly  beds  with  well  preserved  bryozoan  specimens, 
such  as  are  present  in  places  in  some  of  the  outcrops  along  Mississippi  River, 


LOWER    MLSSISSIPPIAN 


105 


have  been  met  with  in  Hardin  County.  The  only  fossils  of  the  formation 
that  have  been  observed  anywhere  in  the  county  in  abundance  and  in  a  good 
state  of  preservation,  are  the  colonies  of  the  coral  genus  Lithostrotion.  Two 
species  of  this  coral  are  present  in  the  fauna.  Near  the  base  of  the  formation 
there  is  present,  locally  at  least,  and  perhaps  wherever  this  part  of  the  forma- 
tion is  exposed,  a  very  conspicuous  coral  bed  in  which  large  colonies  of 
L.  proliferum  occur  in  great  numbers.  One  of  the  best  exposed  outcrops  of 
this  coral  zone  is  along  the  road  running  southwest  from  Illinois  Furnace,  in 
the  SW.  %  SE.  %  sec.  8,  T.  12  S.,  E.  8  E.,  where  it  occupies  a  thickneiss 
of  eight  or  ten  feet  of  limestone.    An  entirely  similar  coral  zone,  characterized 


Pig.  6. — Layer  of  St.  Louis  limestone,  about  75  feet  below  the  top  of  the  forma- 
tion, with  the  fossil  coral  Lithostrotion  proliferum;  river  bank  just  above  low 
water,  three-fourths  of  a  mile  west  of  Cave  in  Rock,  looking  east. 


by  the  same  species,  is  widely  present  near  the  base  of  the  St.  Louis  limestone 
in  the  outcrops  of  the  formation  on  both  sides  of  Mississippi  Eiver  south  of 
St.  Louis.  This  coral  species  also  occurs  at  other  horizons  in  the  formation 
in  Hardin  County,  and  one  of  these  higher  beds,  crowded  with  large  heads 
of  the  branching  coral,  is  exposed  in  the  ledges  on  the  river  bank  at  low 
water,  about  three-fourths  of  a  mile  west  of  Cave  in  Eock  (fig.  6).  Another 
species  of  the  same  genus,  Lithostrotion  canadensis,  is  more  commonly  met 
with  in  the  higher  than  in  the  lower  beds.  The  species  has  not  been  observed 
in  any  one  bed  occurring  in  such  numbers,  however,  as  L.  proliferum  in  the 
coral  zones  mentioned  above.     The  colonies  are  more  or  less  scattered,  and  in 


"LOG  GEOLOGY  OF    HARDIN  COUNTY 

places  considerable  thicknesses  of  limestone  over  large  areas  may  be  wholly 
barren  of  them.  The  most  common  manner  of  occurrence  of  the  species  is 
in  the  form  of  loose,,  silicified  colonies  in  the  chert  residuum  overlying  the 
limestone.  These  two  species  of  Litliostrotion  are  commonly  considered  as 
good  index  fossils  of  the  St.  Louis  limestone,  and  in  Hardin  County,  at  least, 
neither  of  them  has  been  observed  in  any  other  formation. 

Ste.  Genevieve  Limestone 

By  Stuart  Weller 
NAME  AND  DISTRIBUTION 

The  Ste.  Genevieve  limestone  was  first  differentiated  by  Shumard1 
although  no  adequate  description  of  the  formation  was  given  by  him.  The 
name  of  the  formation  was  taken  from  Ste.  Genevieve,  Missouri,  the  type 
locality  specified  by  Shumard  being  in  the  Mississippi  Eiver  bluffs  a  mile  or 
twTo  below  that  town.  For  many  years  following  the  original  definition  of  the 
formation,  both  the  name  and  the  formation  itself  were  overlooked,  and  the 
beds  were  commonly  included  in  the  St.  Louis  limestone. 

When  Ulrich  entered  upon  the  investigation  of  the  lead,  zinc,  and 
fluorspar  region  of  western  Kentucky,  he  differentiated  a  formation  lying 
above  the  St.  Louis  limestone  which  he  designated  as  Princeton  limestone.2 
Later,  a  visit  to  Ste.  Genevieve  convinced  him  that  his  Princeton  limestone 
in  Kentucky,  and  the  Ste.  Genevieve  limestone  of  Shumard  were  the  same, 
and  in  his  final  report  he  adopted  the  older  name  of  the  formation3,  and  gave 
a  much  fuller  description  of  it  than  had  been  published  elsewhere. 

As  the  formation  is  known  at  the  present  time  it  has  a  wide  geographic 
distribution  from  Iowa  to  Alabama.  In  Iowa  it  is  represented  by  the  so- 
called  Pella  beds4,  originally  defined  by  Bain  as  a  subdivision  of  the  St.  Louis 
limestone  of  that  state.  The  formation  is  exposed  at  many  points  in  the 
Des  Moines  Valley  from  Fort  Dodge  to  the  southeastern  corner  of  the  state. 
The  Ste.  Genevieve  limestone  is  well  exposed  in  the  Mississippi  Eiver  bluffs 
at  Alton,  Illinois,  and  at  intervals  on  both  sides  of  the  Mississippi  to  Ste. 
Genevieve  County,  Missouri,  and  to  Union  County,  Illinois.  It  is  exposed 
at  various  localities  in  the  southern  counties  of  the  state,  from  Union  to 
Hardin,  and  extends  into  Kentucky.  East  of  the  coal  fields  the  formation 
again  appears  both  in  Indiana  and  in  Kentucky. 

In  Hardin  County  the  Ste.  Genevieve  occupies  a  larger  areal  extent  than 
any  other  formation,  the  total  area  being  about  35  square  miles,  the  forma- 
tion most  nearly  approaching  it  in  extent  being  the  Pottsville.     The  areas  of 

1  Trans.  St.  Louis  Acad.  Sci.,  vol.   1,  p.   406,    (1859)  ;  Mo.  Geol.  Surv.,  Rept.  for  1855- 
1871,  p.  293    (1873). 

2  Crittenden  Press,  Dec.   1890;  Bull.  U.  S.  Geol.  Surv.,  No.  213,  p.  207    (1903). 

3  Prof.  Paper,  U.  S.  Geol.  Surv.,  No.   36,  p.   39    (1905). 

4Amer.  Geol.,  vol.  15,  p.  318,    (1895)  ;  la.  Geol.  Surv.,  vol.  5,  p.  150,    (1896). 


LOWER    MISSISSIPPIAN  10? 

outcrop  of  the  formation  are  widely  scattered,  and  occur  in  each  one  of  the 
three  structural  regions  that  have  been  described  (see  figure  3).  In  the  south- 
eastern part  of  the  county  the  formation  is  exposed  in  the  Ohio  Eiver  bluffs 
east  of  Cave  in  Eock.  About  one  mile  east  of  the  town  it  is  present  in  the 
upper  part  of  the  bluff,  but  the  eastward  dip  of  the  strata  brings  the  forma- 
tion down  to  river  level  in  a  comparatively  short  distance.  The  exposures 
continue  eastward  for  about  two  miles,  to  the  point  of  the  bluff  at  about 
the  middle  line  of  sec.  17,  T.  12  S.,  E.  10  E.,  except  where  it  is  interrupted 
by  the  rather  broad  valley  from  the  northwest,  the  mouth  of  which  is  about 
one  and  one-half  miles  east  of  Cave  in  Eock.  From  this  outcrop  in  the  Ohio 
Eiver  bluffs  the  belt  occupied  by  the  formation  extends  in  a  northwesterly 
or  nearly  westerly  direction  to  the  first  Peters  Creek  fault,  the  extreme  width 
of  the  outcrop  being  a  little  over  two  miles.  In  a  northeasterly  direction  this 
area  of  Ste.  Genevieve  passes  beneath  the  overlying  Chester  formations  along 
the  line  of  bluffs  that  extend  southeastwardly  from  sec.  33,  T.  11  S.,  E,  9  E., 
to  Ohio  Eiver  two  miles  east  of  Cave  in  Eock.  Along  its  northwestern  border 
this  area  is  limited  by  the  first  of  the  northeast-southwest  Peters  Creek  faults 
that  bounds  the  central  faulted  zone  of  the  county. 

In  the  central  faulted  zone  the  Ste.  Genevieve  limestone  occupies  a  large 
portion  of  belt  number  three  (see  figure  3),  extending  continuously  from 
the  gap  in  the  hills  on  the  line  between  sees.  6  and  7,  T.  12  S.,  E,  9  E.,  to 
Eosiclare.  In  its  northern  part  this  area  is  very  narrow,  occupying  scarcely 
one-fourth  of  a  mile,  but  it  broadens  southwestwardly,  becoming  one  and  one- 
half  miles  wide  where  Big  Creek  crosses  the  belt.  From  its  northeastern 
extremity  nearly  to  Big  Creek  the  limestone  passes  beneath  the  Chester  forma- 
tions in  a  northwestern  direction,  in  normal  contact,  but  beyond  this  point  it 
is  in  fault  contact  with  Chester  formations.  At  the  extreme  southwestern 
extremity  of  the  belt  the  Ste.  Genevieve  again  passes  beneath  the  Chester 
formations  in  normal  contact,  in  the  hill  on  the  Ohio  Eiver  bank  just  below 
Eosiclare.  A  Avedge-shaped  block,  obliquely  truncated  at  its  northeastern, 
narrower  extremity  at  the  line  between  sees.  7  and  18,  T.  12  S.,  E.  9  E.,  and 
extending  to  Ohio  Eiver  between  the  mouth  of  Hosick  Creek  and  Elizabeth- 
town,  is  made  up  entirely,  at  the  surface,  of  Ste.  Genevieve  limestone.  The 
higher  Ste.  Genevieve  limestone  of  the  block  is,  at  its  northern  extremity, 
continuous  to  the  east  with  the  lower  part  of  the  same  formation  in  the  south- 
eastern, unfaulted  portion  of  the  county. 

In  belt  number  two  of  the  faulted  zone  the  Ste.  Genevieve  limestone  is 
present  as  the  surface  rock  in  two  small  areas  only,  the  entire  space  occupied 
being  less  than  one-fourth  of  a  square  mile.  The  most  extensive  of  these 
exposures  is  east  of  Stone  School,  along  the  road  to  Elizabethtown.  The 
greater  part  of  the  area  is  occupied  by  the  Eosiclare  sandstone  which  has  a 
broad  exposure  upon  the  dip  slope,  but  the  Fredonia  limestone  is  also  exposed 


108  GEOLOGY    OF    HARDIN    COUNTY 

in  the  hill  slope  north  of  the  road.  The  only  other  fault  block  in  this  belt  in 
which  the  Ste.  Genevieve  is  exposed,  lies  one-half  mile  north  of  the  iron  bridge 
over  Big  Creek  between  Elizabethtown  and  Eosiclare.  A  large  part  of  the 
block  is  occupied  by  the  formation,  but  it  is  covered  for  the  most  part  with 
the  alluvial  deposits  of  the  Big  Creek  valley,  but  the  Fredonia  is  exposed  in 
the  bank  of  the  creek  in  the  southwestern  part  of  the  block,  and  a  single 
outcrop  of  Eosiclare  sandstone  has  been  observed  towards  the  northwestern 
boundary  of  the  block. 

In  belt  number  one  of  the  faulted  zone  the  Ste.  Genevieve  occupies  two 
areas,  one  on  each  flank  of  the  arch,  with  an  area  of  older,  St.  Louis  lime- 
stone between.  The  northern  of  these  areas  extends  from  the  fault  line  just 
northwest  of  Keelin  School,  in  a  northwesterly  direction  across  Hogthief 
Creek  to  Illinois  Furnace;  from  here  it  extends  in  a  northeasterly  direction 
north  of  Hogthief  Creek,  beyond  Pankeys  Store,  to  the  east  side  of  sec.  3C, 
T.  11  S.,  E.  9  E.  Northward  from  Pankeys  Store  the  formation  extends  to 
the  Wolrab  Mill  fault  in  sec.  27,  T.  11  S.,  E.  8  E.  On  the  southern  limb  of 
this  arch  the  Ste.  Genevieve  occupies  an  area  lying  east,  north,  and  west  of 
St.  Joseph  School,  and  continues  southward  on  the  west  side  of  Wallace 
Branch,  past  Melcher  and  Eich  Hills,  to  the  Ohio  Eiver  bluffs. 

In  the  northwestern  part  of  the  county  the  Ste.  Genevieve  partly  encircles 
the  Hicks  dome,  being  cut  off  to  the  southeast  by  the  Wolrab  Mill  fault. 
Southwest  of  the  dome  towards  Eichorn,  the  width  of  the  Ste.  Genevieve  belt 
is  approximately  two  miles,  while  northwest  of  Hicks  it  is  less  than  one-half 
mile.  It  broadens  out  again  northeast  of  the  dome,  but  in  that  direction 
there  is  an  offset  in  the  outcrop  caused  by  the  Lee  fault. 

Within  these  areas  of  outcrop  of  the  Ste.  Genevieve  formation,  by  far 
the  greater  portion  is  underlain  by  the  Fredonia  limestone  which  is  the 
thick,  lower  member  of  the  formation.  The  best  exhibition  of  the  Fredonia 
member  of  the  Ste.  Genevieve  formation  in  Hardin  County  is  in  the  Ohio 
Eiver  bluffs  just  above  Eosiclare,  where  the  limestone  has  been  extensively 
quarried.  The  upper  portion  of  the  quarry  at  Jacks  Point,,  one  mile  below 
Elizabethtown,  is  also  in  the  Fredonia.  The  basal,  cherty  beds  of  this  member 
are  finely  exhibited  in  the  river  bluff  at  Elizabethtown  in  front  of  the  Eose 
Hotel,  and  for  a  mile  to  the  east  along  the  river  bank.  In  the  northwestern 
part  of  the  region  mapped,  the  best  exhibition  of  the  Fredonia  is  on  Hicks 
Branch  and  Baldwins  Eun,  just  across  the  line  in  Pope  County,  in  the  eastern 
part  of  the  NE.  %  sec.  27,  T.  11  S.,  E.  7  E;.  In  the  southeastern  part  of  the 
county  good  exposures  of  the  Fredonia  may  be  seen  in  the  river  bluffs  east  of 
Cave  in  Eock,  and  a  good  exposure  of  a  large  thickness  of  the  same  limestone 
may  be  seen  at  the  road  corner  near  Love  School,  two  miles  north  of  Cave  in 
Eock.  On  Peters  Creek,  in  the  NW.  %  sec.  8,  T.  12  S.,  E.  9  E.,  twenty  feet 
or  more  of  dark  limestone  is  exposed  that  in  color  and  texture  is  very  like 


LOWER    MISSISSIPPI  AN  109 

the  St.  Louis  limestone,  but  is  believed  to  be  a  locally  developed  dark  facies 
of  the  Fredonia.  The  upper  100  feet  of  the  Fredonia  is  well  displayed  on 
the  west  side  of  Lead  Hill  in  the  NW.  %  sec.  4,  T.  12  S.,  E.  9  E.,  and  the 
Eosiclare  sandstone  and  overlying  "Lower  Ohara"  are  well  exposed  near  and 
on  the  top  of  the  same  hill  at  its  north  end. 

The  Eosiclare  sandstone  outcrop  is  commonly  a  very  narrow  belt,  but  in 
the  southwestern  part  of  the  county,  this  thin  sandstone  member  is  the  surface 
formation  throughout  areas  of  considerable  extent  in  the  neighborhood  of 
Eichorn  and  southward  from  that  place  for  about  three  miles,  where  the  dip 
of  the  rock  strata  nearly  conforms  with  the  slope  of  the  surface.  Another 
area  where  this  sandstone  underlies  a  dip  slope  is  largely  in  sec.  18,  T.  11  S., 
E.  8  E.,  northeast  of  Hicks.  The  outcrop  of  the  "Lower  Ohara"  member  of 
the  formation  is  limited  for  the  most  part,  to  a  very  narrow  belt  just  beneath 
the  overlying  Chester  formations.  The  only  part  of  the  county  where  it  occu- 
pies more  extensive  area  is  in  the  extreme  southwestern  part,  northwest  and 
southwest  of  Melcher  Hills. 

SUBDIVISIONS    OF   THE   STE.    GENEVIEVE   LIMESTONE 

The  Ste.  G-enevieve  limestone  in  Hardin  County  is  divisible  into  three 
persistent  members.  The  great  mass  of  the  formation  is  a  limestone  consti- 
tuting the  lower  member,  to  which  Ulrich  has  applied  the  name  Fredonia. 
This  lower  member  is  followed  by  a  thin,  calcareous  sandstone  designated 
Eosiclare  sandstone  by  the  same  author,  from  its  typical  development  in  the 
Ohio  Eiver  bluff  just  below  the  town  of  that  name  in  Hardin  County.  The 
upper  member  of  the  formation  consists  of  limestone  and  shale.  Ulrich  used 
the  name  "Ohara"  for  the  upper  member  of  the  Ste.  Genevieve  limestone  as 
he  defined  it,  but  the  more  recent  studies  have  shown  that  only  the  lower 
portion  of  the  original  Ohara  is  properly  referable  to  the  Ste.  Genevieve,  the 
higher  portion  being  the  equivalent  of  lower  Chester  formations  in  the  Mis- 
sissippi Valley  section.  In  order  to  remove  the  possibility  of  misunderstand- 
ing and  at  the  same  time  do  away  with  the  necessity  of  introducing  a  new 
stratigraphic  name,  this  higher  member  of  the  Ste.  Genevieve  will  be  desig- 
nated as  "Lower  Ohara"  in  this  report,  although  no  "Upper  Ohara,"  as  such, 
will  be  recognized. 

In  addition  to  these  three  members  of  the  Ste.  Genevieve  formation  first 
recognized  and  named  by  Ulrich,  a  sandstone  member  occupying  a  lower 
position  than  the  Eosiclare  has  been  observed  at  a  number  of  localities  in 
Hardin  County.  The  best  exhibition  of  this  lower  sandstone  member  is  near 
the  boundary  of  the  county  west  of  Eichorn,  where  it  occupies  a  position 
about  fifty  feet  below  the  top  of  the  Fredonia  limestone.  A  similar  sub- 
Eosiclare  sandstone  is  exposed  about  two  and  one-half  miles  southeast  of 
Eichorn,  and  still  another  localitv  is  three  miles  northwest  of  Cave  in  Eock, 


110  GEOLOGY  OF  HARDIN  COUNTY 

in  the  NW.  %  sec.  3,  T.  12  S.,  E.  9  E.,  where  a  cross-bedded,  calcareous, 
fossiliferous  sandstone  lies  40  feet  below  the  Eosiclare  sandstone,  both  sand- 
stones being  well  exposed  in  the  same  section. 

Outside  of  Hardin  County  the  typical  three-fold  division  of  the  Ste. 
Genevieve  formation  is  developed  across  Ohio  Eiver  in  Kentucky.  In 
the  type  region  of  the  formation,  Ste.  Genevieve  County,  Missouri,  and 
extending  into  northern  Perry  County,  a  median  sandstone  member,  with 
limestone  below  and  above,  is  present  locally  in  the  Ste.  Genevieve  forma- 
tion, while  elsewhere  such  a  sandstone  member  is  wholly  wanting.  The  same 
condition  holds  in  Monroe  County,  Illinois,  where  a  sandstone  member  is 
present  in  some  sections  and  absent  in  others,  and  a  similar  sandstone  mem- 
ber is  present  in  the  section  at  Alton,  Illinois. 

Whether  the  sandstone  member  of  the  Ste.  Genevieve  formation  in  the 
Mississippi  Valley  localities  is  the  exact  equivalent  of  the  Eosiclare  sandstone 
of  Hardin  County,  or  of  the  sub-Eosiclare  sandstone,  or  indeed  whether  it 
is  not  something  different  from  either  of  these  beds,  cannot  now  be  certainly 
determined. 

LITHOLOGIC  CHARACTERS   OF   THE  FREDONIA   LIMESTONE  MEMBER 

The  Fredonia  member  of  the  Ste.  Genevieve  formation  is  a  massive  lime- 
stone in  which  the  beds  vary  considerably  in  lithologic  character.  The  color 
ranges  from  blue-gray,  to  gray,  or  even  to  nearly  white,  on  the  whole  a 
distinctly  lighter  color  than  that  of  the  St.  Louis  limestone.  The  texture  of 
the  limestone  is  also  variable,  dense,  compact  beds  which  exhibit  a  conchoidal 
or  splintery  fracture,  not  unlike  some  of  the  beds  of  the  underlying  St.  Louis 
Jimestone,  alternating  with  other  more  typical  strata.  The  most  notable 
feature  of  the  member  is  its  oolitic  character ;  in  fact  Ulrich  originally  called 
it  the  Fredonia  oolite  member  of  the  Ste.  Genevieve.  In  the  lower  portion  of 
the  member,  towards  its  contact  with  the  St.  Louis  limestone,  the  oolitic 
beds  are  less  conspicuous  than  in  the  higher  portion,  where  some  thick, 
apparently  persistent,  nearly  white  oolitic  beds  are  present  in  all  the  sections 
of  Hardin  and  other  southern  Illinois  counties,  as  well  as  in  Kentucky.  In 
the  upper  portion  of  the  Fredonia,  in  some  sections,  there  are  some  thin  beds 
of  calcareous  shales,  which  in  Hardin  County  are  scarcely  more  than  shaly 
partings  between  some  of  the  denser  limestone  strata.  Some  of  the  limestone 
beds  are  distinctly  cross-bedded  in  structure.  The  formation  contains  a  large 
amount  of  chert,  some  of  which  resembles  that  of  the  St.  Louis  limestone, 
but  in  general  the  Ste.  Genevieve  chert  occurs  in  plate-like  masses,  much 
more  regular  and  smoother  in  outline  than  those  of  the  older  limestone.  The 
chert  is  apt  to  be  more  conspicuously  developed  in  the  lower,  less  oolitic 
portion  of  the  formation,  but  in  places  persists  to  the  summit  of  the  lime- 
stone.    The  chert  in  the  lower  part  of  the  Fredonia  is  best  displayed  in  the 


LOWER    MISSISSIPPIAN 


111 


Ohio  River  bluffs,  especially  at  Elizabethtown  and  vicinity,  and  a  typical 
expression  of  the  chert  of  this  part  of  the  formation  is  shown  in  figures  7 
and  8. 

LITHOLOGIC    CHARACTER   OF    THE    ROSICLARE   SANDSTONE    MEMBER 

The  Rosiclare  sandstone  member  of  the  Ste.  Genevieve  formation  is  a 
thin  but  persistent  bed  throughout  the  area  of  outcrop  of  the  formation  in 
Hardin  County,  and  in  the  adjacent  parts  of  Illinois  and  Kentucky.  Where 
the  sandstone   is  met  with  in  the  excavations  of  mine  shafts  it   is  highly 


Pig.  7. — Photograph  of  the  limestone  bluff  in  front  of  the  Rose  Hotel,  Eliza- 
bethtown, Illinois,  showing  the  dark  cherty  layers  in  the  lower  part  of  the 
Fredonia  limestone.  The  chert  itself  is  superficial,  being  formed  by  the  silicifica- 
tion  of  the  limestone  layers  to  the  depth  of  only  an  inch  or  two.  Looking 
northwest. 


calcareous,  and  in  places  it  might  be  taken  for  a  limestone  with  an  abundance 
of  included  sand  grains.  Where  the  bed  has  been  subjected  to  weathering  the 
lime  has  been  entirely  leached  out,  leaving  a  rather  fine  grained  but  very 
porous  sandstone.  Where  the  rock  has  been  unaffected  by  weathering  its 
color  is  gray,  not  uncommonly  with  a  slight  greenish  or  bluish  tint,  but  upon 
weathering  it  becomes  brown,  as  in  the  bluff  just  below  Rosiclare,  and  where 
the  weathering  has  proceeded  farther  and  the  formation  occurs  in  residual 
masses,  as  it  does  over  a  considerable  area  east  of  Eichorn,  it  commonly 
exhibits  a  distinctly  reddish  brown  color.  Wherever  seen  in  section  the  Rosi- 
clare exhibits  notable  cross-bedding.     In  the  NW.  %  sec.  36,  T.  12  S.,  R.  8 


112  GEOLOGY   OF    HARDIN    COUNTY 

E.,  the  Eosiclare  is  especially  coarse  and  thick-bed decl,  and  carries  a  few 
small  quartz  pebbles.  On  the  top  of  Lead  Hill  it  is  rather  laminated  and 
cross-bedded. 

LITHOLOGIC    CHARACTERS    OF    THE    "LOWER    OHARA^    LIMESTONE    MEMBER 

The  "Lower  Ohara"  limestone  member,  overlying  the  Eosiclare  sand- 
stone, is  not  notably  different  from  the  Fredonia  below  the  sandstone.  It  is 
commonly  oolitic  or  semi-oolitic  in  texture,  light  in  color,  in  places  nearly 


Fig.  8. — Cherty  Ste.  Genevieve  limestone  half  a  mile  east  of  Elizabethtown. 

white,   and  it   also/  may  include   some  beds   which  are   dense  and  compact, 
resembling  similar  beds  in  the  Fredonia. 

DETAILED    SECTIONS 

The  only  considerable  continuously  exposed  section  of  the  Ste.  Genevieve 
formation  in  Hardin  County  which  has  been  carefully  measured,  is  the  section 
at  Eosiclare,  in  the  Ohio  Eiver  bluffs.  This  section  includes  more  than  the 
Ste.  Genevieve,  however,  and  continues  up  into  the  overlying  formations,  and 
as  measured  it  does  not  continue  to  the  base  of  the  Fredonia  member  of  the 
formation.  The  lower  part  of  the  section,  up  to  the  base  of  the  Eosiclare 
sandstone  member,  is  exposed  in  the  bluff  quarries  just  above  the  boat  land- 
ing, the  higher  portion  being  exposed  below  the  town  at  Downeys  and  Fair- 
view  bluffs. 


LOWER   MISSISSIPPIAN  113 

Section  of  the  Ste.  Genevieve  limestone  and  Lower  Chester  formations  at  Rosiclare 

Thickness 
Feet 
19.     Sandstone,    coarse    grained,    yellow-brown    to    ferruginous    in    color, 

with  numerous  fragments  of  plant  stems   (Bethel  sandstone) 50 

18.     Talus-covered,  blocks  of  Bethel  sandstone,  no  limestone  exposed....  40 

17.     Limestone    with    shale    partings.      Limestone    beds    mostly    gray    in 
color,  crystalline  in  texture,  fossiliferous.     Pentremites  abundant; 

Lyropora  and  Talarocrinus 26 

16.     Talus-covered,  but  probably  shale  and  limestone  interbedded,  with 

shale    predominating 30 

15.     Limestone,  gray,  crystalline,  cross-bedded 4 

14.     Shale  and  limestone  interbedded,  the  limestone  more  or  less  argil- 
laceous, gray,  crystalline,  conspicuously  cross-bedded,  passing  into 

shale  laterally.     Shale  abundantly  fossiliferous 6 

(Unconformity) 
13.  Limestone,  oolitic,  semi-oolitic,  and  dense  in  texture,  some  beds 
cross-bedded,  others  not.  Fossils  not  well  preserved,  but  many 
of  the  weathered  surfaces  covered  with  crinoid  stem  segments, 
among  which  are  those  of  Platycrinus  penicillus,  with  an 
occasional   base   of   the   same    species    ("Lower   Ohara"    limestone 

member )     35 

12.     Sandstone,  calcareous,  gray-brown  in  color  when  fresh,  yellow-brown 
when  weathered,  conspicuously  cross-bedded   (Rosiclare  sandstone 

member )     10 

11.     Talus-covered,   possible    interval   of 10 

10.     Limestone,  dense,  gray,  oolitic,  with  smooth  weathered  surface 13 

9.  Limestone,  in  part  oolitic,  and  in  part  dense  and  brittle,  shaly  part- 
ings, fossiliferous,  with  Pugnoides  ottumwa 4 

8.     Limestone,  bluish-gray  in  color,  oolitic,  fossiliferous 4 

7.     Limestone,  gray,  oolitic iy2 

6.     Limestone,  dark  blue  to  gray   in  color,   evenly  bedded,   with   shaly 

partings.      Fossiliferous 7 

5.     Limestone,  white,  oolitic,  lower  portion  with  numerous  crinoid  stems 

on   weathered   surface.     Fossiliferous 30 

4.  Limestone,  blue-gray  to  blue-black  in  color,  with  inconspicuous 
bedding  planes.  Some  parts  crystalline,  others  compact  in  texture 
with  splintery  fracture.     Fossiliferous,  with  Pugnoides  ottumwa..  15 

3.  Limestone,  without  chert,  mostly  gray  in  color,  some  beds  crystalline, 
others  oolitic,  certain  thin  beds  buff  in  color,  apparently  dolo- 
mitic.  Fossils  poorly  preserved,  but  some  weathered  surfaces 
covered   with  crinoid   stems,   among  them  Platycrinus  penicillus, 

with  an  occasional  base  of  the  same  species 27 

2.     Unexposed    interval    3 

1.     Limestone,  cherty,  more  or  less  compact  in  texture 

THICKNESS 

The  greater  portion  of  the  Ste.  Genevieve  formation  is  included  in  the 
Fredonia  member,  which  is  at  least  180  feet  in  thickness  in  the  Ohio  Kiver 
—8  G 


114  GEOLOGY    OF    HARDIN    COUNTY 

bluffs  between  Eosiclare  and  Jacks  Point  at  the  mouth  of  Big  Creek.  The 
thickness  of  the  member  may  be  somewhat  greater  than  this,  and  it  is  alto- 
gether probable  that  a  maximum  thickness  of  200  feet  is  not  excessive.  Three 
to  four  miles  north  of  Elizabethtown,  in  the  region  adjacent  to  Hogthief 
Creek,  the  Fredonia  appears  to  be  only  120  to  150  feet  thick,  and  the  basal 
beds  in  this  region  differ  somewhat  in  character  from  those  in  the  river  bluff 
at  Elizabethtown.  The  Eosiclare  sandstone  member  of  the  formation,  in  its 
type  exposure  below  Eosiclare,  is  about  16  feet  thick.  In  the  shaft  of  the 
Stewart  mine,  south  of  Eichorn,  22  feet  of  the  sandstone  was  passed  through, 
and  in  the  region  east  and  southeast  of  Eichorn,  where  the  bed  is  conspicuously 
developed,  the  thickness  may  be  somewhat  greater  than  this,  probably  25  to 
30  feet.  On  the  contrary,  locally,  the  bed  may  be  thinner  than  in  the  type 
section  at  Eosiclare,  for  in  one  section  in  Kentucky  only  two  feet  is  exhibited. 
Fifteen  to  twenty  feet  is  doubtless  a  fair  estimate  of  the  average  thickness  of 
the  bed.  The  "Lower  Ohara"  member  of  the  formation  varies  in  thickness 
from  twenty  feet  and  even  less,  to  as  much  as  fifty  feet,  about  25  feet  being 
the  average.  The  combined  thickness  of  the  three  members  of  the  Ste. 
Genevieve  formation  may  be  as  much  as  300  feet,  although  in  places  it  prob- 
ably does  not  exceed  250  feet. 

STRATIGRAPHIC  RELATIONS 

The  stratigraphic  relations  of  the  Ste.  Genevieve  limestone  with  the 
underlying  St.  Louis  have  already  been  discussed.  Sedimentation  from  the 
older  to  the  younger  formation  was  apparently  continuous,  with  no  strati- 
graphic  break  in  Hardin  County;  consequently  the  boundary  line  between 
the  two  formations  has  to  be  drawn  more  or  less  arbitrarily.  At  one  time  it 
was  believed  that  the  conspicuously  cherty  beds  were  limited  to  the  St. 
Louis  formation,  but  further  observation  has  shown  this  criterion  to  be  use- 
less, for  in  places  there  are  abundant  cherts  to  the  top  of  the  Fredonia.  The 
oolitic  character  of  the  limestone  is  a  much  safer  criterion  for  the  recognition 
of  the  Ste.  Genevieve  than  is  the  absence  of  chert,  and  it  has  been  the  practice 
in  Hardin  County  to  draw  the  boundary  line  between  these  two  formations 
below  the  lowest  oolite  beds  observed.  Not  all  the  beds  of  the  Fredonia  lime- 
stone are  oolitic,  however,  and  the  oolitic  character  of  the  formation  becomes 
more  marked  in  the  higher  part  of  the  formation,  but  in  the  undoubted  St. 
Louis  limestone  no  oolitic  beds  of  any  sort  have  been  noticed  in  the  county. 

One  very  characteristic  fossil,  the  stem  plates  of  a  crinoid  of  the  genus 
Platycrinus,  characterized  by  their  elliptical  outline,  and  by  a  series  of 
marginal  spine-like  processes,  has  been  considered  as  highly  characteristic  of 
the  Ste.  Genevieve  limestone,  and  wherever  these  plates  are  observed  in 
abundance  it  is  safe  to  consider  the  limestone  as  belonging  in  that  formation; 
but  crinoid  plates  of  the  same  species  do  occur,  though  more  rarely,  in  lower 


LOWER    MISSISSIPPIAN 


115 


beds  which  can  be  only  St.  Louis.    On  the  other  hand  these  plates  are  entirely 
unknown  above  the  "Lower  Ohara"  limestone. 

The  boundary  line  between  the  Ste.  Genevieve  and  the  next  succeeding 
formation  is  an  unconformable  surface  in  every  section  observed  where  the 
contact  can  be  seen.  This  is  true  not  only  in  the  counties  adjacent  to  Mis- 
sissippi River;  but  also  in  the  southern  Illinois  counties  and  in  the  adjoining 
part  of  Kentucky.  In  Hardin  County  the  unconformity  is  perhaps  best  shown 
in  the  section  above  the  railroad  incline  of  the  Fairview  mine,  at  Fairview 
bluff.  The  same  unconformity  with  conglomeratic  beds  in  the  basal  portion 
of  the  higher  formation  is  also  exhibited  in  the  sections  east  of  Shetlerville, 
between  that  place  and  Wallace  Branch.  In  the  Cedar  Bluff  section,  near 
Princeton,  Kentucky,  the  same  unconformable  surface  is  marked  by  a  distinct 
basal  conglomerate  in  the  limestone  overlying  the  Ste.  Genevieve,  the  size 
of  the  limestone  pebbles  commonly  being  from  two  inches  to  fragments  the 
size  of  peas. 


PALEONTOLOGY 


Much  of  the  limestone  of  the  Ste.  Genevieve  formation  in  Hardin  County 
is  not  of  a  character  to  preserve  fossils  in  such  a  condition  that  they  can  be 
easily  collected  and  identified,  although  the  weathered  surfaces  commonly 
exhibit  an  abundance  of  organic  remains.  Crinoid  stem  segments  are  par- 
ticularly abundant  upon  many  of  the  weathered  surfaces,  and  one  of  the 
commonest  of  these  is  a  small  form,  elliptical  in  outline,  with  a  major 
diameter  of  an  eighth  of  an  inch  or  less,  and  with  the  border  ornamented  with 
a  row  of  spines  resembling  the  handles  in  the  rim  of  a  ship's  steering  wheel. 
The  basal  plates  of  the  cup  belonging  with  these  stem  segments  are  also  met 
with  in  many  places,  but  they  are  much  less  frequent  than  the  stems;  they 
are  characterized  by  three  ribs  radiating  outward  from  the  stem  facet.  This 
crinoid  commonly  has  been  identified  as  Platycrinus  huntsvilUe,  but  it  is 
perhaps  more  properly  referred  to  P.  penicillus  M.  &  W.,  originally  described 
from  Hardin  County,  from  "St.  Louis  division  of  the  Lower  Carboniferous 
series."  In  places  these  remains  are  represented  by  innumerable  examples, 
elsewhere  they  are  less  common  or  even  wanting,  but  in  no  section  of  the  Ste. 
Genevieve  limestone  in  Hardin  County  has  diligent  search  failed  to  discover 
them.  These  stem  segments  are  more  abundant  in  the  higher  portion  of  the 
Fredonia  member  of  the  formation  than  in  the  lower  part,  but  they  are  present, 
and  in  places  abundant,  to  its  base,  and  are  also  locally  met  with  in  the  sub- 
jacent St.  Louis  limestone.  This  same  crinoid  species,  represented  by  the 
same  sort  of  material  upon  the  weathered  surfaces  of  the  limestone,  is  present 
in  the  "Lower  Ohara"  limestone  at  the  summit  of  the  formation. 

In  some  portions  of  the  Fredonia,  certain  corals  occur  commonly.     The 
one  most  often  met  with  is  MicheUnia  princetonensis,  weathered-out  speci- 


116 


GEOLOGY  OF  HARDIN  COUNTY 


mens  of  which  may  be  looked  for  in  many  localities  among  the  fragments  of 
residual  chert.  A  search  near  the  top  of  the  hill  just  outside  of  Elizabeth- 
town,  along  the  road  running  north  from  the  town,  has  rarely  failed  to  supply 
a  number  of  specimens  of  this  species.  Specimens  have  also  been  found 
among  the  cherts  by  the  roadside  on  the  hill  between  Elizabethtown  and  the 
Big  Creek  bridge,  and  at  a  number  of  points  in  similar  situations  along  the 
road  between  Elizabethtown  and  Cave  in  Eock,  and  on  the  river  bluff  east  of 
Cave  in  Eock.  The  only  locality  in  the  county  where  this  coral  has  been 
observed  undisturbed  in  the  limestone  ledges,  is  along  the  Ohio  Elver  bank 
just  below  Jenkins  Point,  about  one  mile  above  Eosiclare,  wherei  it  must 
occupy  a  position  fully  180  feet  below  the  Eosiclare  sandstone.  The  range  of 
the  species,  however,  is  apparently  throughout  the  entire  thickness  of  the 
Fredonia,  for  some  of  the  weathered-out  specimens  have  been  collected  in  such 
situations  that  they  must  have  originated  very  close  to  the  base  of  the  Eosi- 
clare sandstone.  Other  Fredonia  corals  less  commonly  met  with  than  the 
Michelinia  princetonensis,  are  Michelinia  subramosa  and  Cystelasma  quinque- 
septata.  The  only  good  examples  of  these  species  collected  in  Hardin  County 
are  from  a  bed  about  40  feet  below  the  Eosiclare  sandstone,  at  a  locality  one- 
half  mile  north  of  the  bridge  across  Big  Creek,  but  the  same  two  species  have 
been  recognized  by  Mr.  Butts,  together  with  Pugnoides  ottumwa  and  examples 
of  Pentremites,  in  the  sandstone  40  feet  below  the  Eosiclare,  at  the  locality 
northwest  of  Cave  in  Eock,  in  the  NW.  %  sec.  3,  T.  12  S.,  E.  9  E.,  already 
mentioned.  Lithostrotion  harmodites,  a  Fredonia  coral  that  occurs  rather 
commonly  in  this  limestone  in  some  Kentucky  localities,  has  not  yet  been 
observed  in  Hardin  County,  but  it  may  be  looked  for  and  doubtless  will  be 
found  later. 

Considerable  collections  of  fossils  have  been  made  from  a  number  of  beds 
of  the  Fredonia  limestone  in  the  river  bluffs  near  Eosiclare.  From  a  bed 
approximately  160  feet  below  the  Eosiclare  sandstone  the  following  species 
have  been  identified : 


Fossils  from  the  Fredonia  limestone  member,  160  feet  below  the  Rosiclare  sandstone 


Platycrinus  penicillus  M.  and  W. 
Dizygocrinus  sp.  undet. 
Orthotetes   sp. 
Productus   ovatus  Hall 
Productus  parvus  M.  and  W. 
Pugnoides  ottumwa  (White)? 
Girtyella  brevilobata  (Swallow) 
Dielasma  formosa    (Hall) 

From  a  bed  22  feet  higher  in  the  section,  or  at  a  horizon  138  feet  below 
the  Eosiclare,  the  following  species  have  been  collected  : 


Spiriferina   transversa    (McChesney) 
Spirifer  pellaensis  Weller 
Cliothyridina  aff.  sublamellosa  (Hall) 
Composita  trinuclea   (Hall) 
Myalina  sp. 
Bellerophon  sp. 
Naticopsis  sp. 


LOWER   MISSISSIPPIAN 


117 


Fossils  from  the  Fredonia  limestone  member,  138  feet  below  the  Rosiclare  sandstone 


Pentremites   princetonensis    Ulrich 

Girtyella  indianensis  (Girty) 

Spiriferina  sp. 

Eumetria  verneuiliana    (Hall) 

Cliothyridina  aff.  sublamellosa  (Hall) 

Composita  trinuclea   (Hall) 

Nucula  shumardana  Hall 

Myalina  sp. 

Liopteria  n.sp. 

Sphenotus  sp. 

Cypricardella   sp. 

Still  higher,  from  a  horizon  85  feet 
section  on  page  113)  we  have  the  followin 


Lepetopsis   levettei   White 

Naticopsis  sp. 

Naticopsis  sp. 

Straparollus  sp. 

Eotrochus  n.sp. 

Bellerophon  sp. 

Bulimorpha  whitfieldi  Weller 

Bulimorpha  sp. 

Zygopleura  sp. 

Laevidentalium  venustus  M.  and  W. 

Orthoceras  sp. 

below  the  Rosiclare,  (Bed  No.  1  in 
g  fauna. 


Fossils  from  the  Fredonia  limestone  member,  85  feet  below  the  Rosiclare  sandstone 


Triplophyllum  sp. 

Pentremites  sp.,  cf.  P.  princetonensis 

Ulrich 
Platycrinus  penicillus  M.  and  W. 
Archaeocidaris  sp.   (spine) 
Stenopora  montifera  Ulrich? 
Orthotetes       kaskaskiensis       (Mc- 

Chesney) 
Productus  ovatus  Hall 


Pustula  sp. 

Pugnoides   ottumwa    (White) 

Girtyella  indianensis    (Girty) 

Dielasma  sp. 

Spirifer  pellaensis   Weller 

Spirifer  leidyi  N.  and  P. 

Cliothyridina  aff.  sublamellosa  (Hall) 

Composita   trinuclea    (Hall) 

Bellerophon  sp. 


Productus  parvus  M.  and  W. 

The  highest  Fredonia  collection  secured  in  the  Rosiclare  section  is  from 
a  horizon  30  feet  below  the  Rosiclare  sandstone,  (Bed  No.  6,  in  section  on 
page  113)  where  the  following  species  have  been  recognized: 


Fossils  from  the  Fredonia  limestone  member,  30  feet  below  the  Rosiclare  sandstone 


Pentremites  princetonensis  Ulrich 
Platycrinus  penicillus  M.  and  W. 
Dizygocrinus  persculptus  Ulrich 
Fistulipora  sp. 

Stenopora  tuberculata   (Prout) 
Fenestella  serratula  Ulrich 
Fenestella  tenax  Ulrich 
Thamniscus  furcillatus  Ulrich 
Septopora  n.sp. 
Rhombopora  sp. 

Orthotetes      kaskaskiensis       (Mc- 
Chesney) 

A  complete  list  of  these  species, 
shown  in  the  following  table: 


Diaphragmus  n.sp. 
Rhipidomella  dubia   (Hall) 
Pugnoides  ottumwa   (White) 
Girtyella  indianensis   (Girty) 
Spiriferina  transversa  (McChesney) 
Spiriferina  cf.  spinosa  (N.  and  P.) 
Spirifer  leidyi  N.  and  P. 
Reticularia  setigera    (Hall) 
Cliothyridina  aff.  sublamellosa  (Hall) 
Composita   trinuclea    (Hall) 


with  their  distribution  in  the  section,  is 


118 


GEOLOGY    OF    HARDIN    COUNTY 


Fossils  from  the  Fredonia  limestone  member  of  the  Ste.  Genevieve  formation,  in 
the  river  bluffs  near  Rosiclare 


Fossils 


From  a 

From  a 

From  a 

bed  160 

bed  138 

bed  85 

feet  below 

feet  below 

feet  below 

the 

the 

the 

Rosiclare 

Rosiclare 

Rosiclare 

sandstone 

sandstone 

sandstone 

From  a 

bed  30 

feet  below 

the 
Rosiclare 
sandstone 


Triplophyllum  sp 

Pentremites  princetonensis  Ulrich 

Platycrinus  penicillus  M.  and  W 

Dizygocrinus  persculptus  Ulrich 

Archaeocidaris  sp.  (spine) 

Fistulipora  sp. . . . . . 

Stenopora  tuberculata  (Prout)    

Stenopora  montifera  Ulrich? 

Fenestella  serratula  Ulrich 

Fenestella  tenax  Ulrich 

Thamniscus  furcillatus  Ulrich 

Septopora  n.  sp 

Rhombopora  sp 

Orthotetes  kaskaskiensis^  (McChesney) 

Orthotetes  sp 

Productus  ovatus  Hall 

Productus  parvus  M.  and  W 

Diaphragmus  sp 

Pustula  sp 

Rhipidomella  dubia  (HalO. 

Pugnoid«ls  ottumwa  (White) 

Girtyella  indianensis  (Girty) 

Girtyella  brevilobata  (Swallow) 

Dielasma  formosa  (Hall) 

Dielasma  sp 

Spiriferina  transversa  (McChesney) 

Spiriferina  cf.  spinosa  (N.  and  P.) 

Spiriferina  sp 

Spirifer  pellaensis  Weller 

Spirifer  leidyi  N.  and  P 

Reticulata  setigera  (Hall) 

Eumetria  verncuiliana  (Hall) 

Cliothyridina  aff .  sublamellosa  (Hall).  . 

Composita  trinuclea  (Haii).. 

Nucula  shumardana  Hall 

Myalina  n.  sp 

Myalina  sp 

Liopteria  n.  sp 

Sphenotus  sp 

Cypricardella  sp 

Lepetopsis  levettei  White '. 

Naticopsis  sp 


X 


X 


X 


X 


X 


LOWER    MISSISSIPPIAN 


119 


Fossils  from  the  Fredonia  limestone  member  of  the  Ste.  Genevieve  formation,  in 
the  river  bluffs  near  Rosiclare — Concluded 


From  a 
bed  30 
feet  below 
Fossils  the  the  the  the 

Rosiclare 
sandstone 


From  a 

From  a 

From  a 

bed  160 

bed  138 

bed  85 

feet  below 

feet  below 

feet  below 

the 

the 

the 

Rosiclare 

Rosiclare 

Rosiclare 

sandstone 

sandstone 

sandstone 

Naticopsis  sp 

Naticopsis  sp 

Straparollus  sp 

Eotrochus  n.  sp 

Bellerophon  sp 

Bellerophon  sp 

Bellerophon  sp 

Bulimorpha  whitfieldi  Weller 

Bulimorpha  sp 

Zygopleura  sp 

Laevidentalium  venustus  (M.  and  W.) 
Orthoceras  sp 


X 


X 


X 


X 


The  Rosiclare  sandstone  is  commonly  entirely  barren  of  fossils,  but 
specimens  of  Eumetrva,  have  been  observed  in  it  at  a  locality  one-half  mile 
southwest  of  Gross,  and  crinoid  plates  and  a  few  obscurely  preserved  brachio- 
pod  shells  have  been  collected  by  Butts  in  the  center  of  sec.  30,  T.  12  S., 
R.  9  E. 

The  "Lower  Ohara"  limestone  is  abundantly  fossiliferous,  the  weathered 
surfaces  of  the  formation  being  covered,  in  many  localities,  with  crinoid  stem 
fragments  and  other  broken  fossils,  but  the  rock  is  of  such  a  nature  that  fossils 
in  a  proper  condition  for  determination  are  difficult  to  obtain.  A  small  col- 
lection has  been  secured  from  the  exposures  at  Fairview  bluffs,  just  below 
Rosiclare,  and  the  following  species  have  been  recognized  from  Bed  'No.  13  of 
the  section  on  page  113  : 


Fossils  from  the  "Lower  Ohara''  limestone  member  of  the  Ste.  Genevieve  formation, 

at  Fairview  bluff 


Platycrinus  penicillus  M.  and  W. 
Spirifer  bifurcatus  Hall 
Spirifer  pellaensis  Weller 
Composita   trinuclea    (Hall) 
Nucula  illinoiensis  Worthen 
Led  a  curta  M.  and  W. 
Cypricardella  oblonga  Hall 
Cypricardinia  indianensis  Hall 


Laevidentalium    venustum     (M.    and 

W.) 
Bellerophon  monroensis  Weller? 
Bucanopsis  textilis   (Hall) 
Aclisina  pygmaea   (Weller) 
Aclisina  sp. 

Orthonychia  acutirostra    (Hall) 
Phillipsia  sp. 


120 


GEOLOGY  OF  HARDIN  COUNTY 


The  stem  segments  of  Platycrinus  penicillus  are  common  upon  the 
weathered  surfaces  at  this  locality.  The  fossils  most  commonly  found  upon 
breaking  up  the  hard,  oolitic  limestone,  are  the  diminutive  gastropods  and 
pelecypods  which  are  listed.  Of  the  thirteen  forms  recorded  whose  specific 
determination  is  certain  or  nearly  certain,  eight  are  present  in  the  Ste. 
Genevieve  limestone  fauna  which  has  been  described  by  Weller  from  Monroe 
County,  Illinois.1  Of  the  other  five  species,  three,  Spirifer  bifurcatus,  Bu- 
canopsis  textilis  and  Orthonychia  acutirostre,  are  common  forms  in  the 
Spergen  limestone,  and  the  other  two,  Platycrinus  penicillus  and  Spirifer 
pellaensis,  are  well  known  Ste.  Genevieve  limestone  forms.  Not  a  single 
member  of  the  fauna  is  a  distinctive  Chester  type,  although  the  two  species 
of  Spirifer  have  near  relatives  in  the  Lower  Chester  faunas.  Spirifer  hifur- 
catus of  the  Spergen  limestone  is  similar  to  S.  leidyi  from  the  Chester,  but 
the  specimen  under  consideration  is  more  like  the  older  Spergen  limestone 
form  than  the  Chester  S.  leidyi.  Spirifer  pellaensis  is  a  close  relative  of  the 
early  Chester  varieties  of  S.  increbescens. 

1  Contributions  from  Walker  Mus.,  vol.   1,  No.   10,    (1916). 


CHAPTER  VIII— UPPER   MISSISSIPPIAN   SERIES,   CHESTER 

GROUP 

By  Stuart  Weller 


General  Statement 

The  Chester  has  long  been  recognized  as  one  of  the  divisions  of  the 
Mississippian  system,  or  the  "Subcarboniferous"  as  it  was  formerly  called,  in 
the  geological  section  of  Illinois.  Until  recent  years  it  has  been  considered 
as  coordinate  in  rank  with  such  formations  as  the  Burlington,  Keokuk,  or 
St.  Louis  limestones,  no  attempt  being  made  by  the  earlier  geologists  to  sub- 
divide the  "formation"  as  it  was  called,  although  it  was  known  that  the 
Chester  was  considerably  thicker  than  the  older  recognized  members  of  the 
Mississippian.  It  was  observed  at  an  early  date  that  the  Chester  section  of 
the  southern  counties  of  Illinois,  viz.,  Union,  Johnson,  Pope,  and  Hardin,  is 
notably  different  in  detail  from  that  of  the  typical  Randolph  County  area 
described  by  Hall  and  by  Worthen,  but  no  serious  effort  was  made  to  corre- 
late the  several  members  of  the  group  in  the  two  areas.  In  order  to  bring 
the  situation  clearly  before  the  reader  of  this  report  it  seems  best  to  outline 
briefly  the  historical  development  of  our  knowledge  of  the   Chester  group. 

Historical  Review 

David  Dale  Owen  was  the  first  geologist  to  make  use  of  the  name  Archi- 
medes limestone1,  in  connection  with  his  "Geological  Reconnaissance  of  the 
State  of  Indiana,  made  in  the  year  1837."  The  Indiana  beds  so  designated 
by  him  were  a  part  of  the  stratigraphic  series  now  known  as  the  Chester 
group.  The  same  author,  in  1852,  used  the  name  again2  for  one  of  the 
divisions  in  his  "Section  of  Subcarboniferous  Limestones  of  Iowa."  The 
Iowa  beds  to  which  the  name  was  applied  constitute  the  Keokuk  limestone  of 
later  authors,  Owen  having  overlooked,  apparently,  the  much  more  con- 
spicuous Archimedes-bearing  bed  of  the  Warsaw  formation.  Owen  seems  to 
have  had  the  idea  that  the  Archimedes-bearing  beds  of  Iowa  were  equivalent 
to  those  with  which  he  was  familiar  in  Indiana. 

In  1855  Swallow3  used  the  name  for  beds  exposed  near  the  mouth  of 
Des  Moines  River  in  northeastern  Missouri,  and  for  similar  beds  in  Marion 

*Geol.  Reconn.  State  of  Indiana,    (1838),  pp.  20-21  of  reprint   (1859). 

2  Geol.  Survey  Wisconsin,  Iowa  and  Minnesota,  p.  92   (1852). 

3  Missouri  Geol.   Surv.,  First  and  Second  Repts.,   pt.    1,  p.   95,  and  section   14,  opposite 
p.  92;  also  pp.   174  and  194    (1855). 

121 


122  GEOLOGY    OF    HARDIN    COUNTY 

and  Cooper  counties,  Missouri,  which  are  referable  to  the  Keokuk  and  Warsaw 
formations  of  more  recent  authors.  With  this  usage  the  name  had  been 
applied  to  beds  at  three  distinct  horizons,  as  the  Mississippian  sections  have 
come  to  be  divided  in  more  recent  years.  Again  in  the  same  Missouri  report, 
Swallow1  designated  as  "Archimedes  Limestone,"  certain  limestones  in  St. 
Louis  County,  Missouri,  lying  beneath  the  St.  Louis  limestone,  which  are  now 
included  in  the  Spergen  formation,  this  being  a  still  different  horizon  from 
any  of  the  three  to  which  the  name  had  been  applied  by  Owen  or  Shumard. 
The  name  was  used  by  Swallow,  not  because  the  beds  which  he  so  designated 
were  characterized  by  numerous  specimens  of  Archimedes,  for  they  are  rare, 
but  because  he  believed  these  limestones  of  St.  Louis  County  occupied  the 
same  stratigraphic  position  as  those  to  which  the  name  had  been  applied  in 
northeastern   Missouri. 

The  disentanglement  of  these  several  "Archimedes  limestones"  was 
accomplished  by  Hall  in  connection  with  his  work  in  Iowa  and  southward 
along  the  Mississippi  River  sections  in  Illinois  and  Missouri.  In  the  first 
statement  of  the  results  of  Hall's  work2,  read  before  the  tenth  meeting  of  the 
American  Association  for  the  Advancement  of  Science,  in  August  1856,  the 
stratigraphic  succession  of  the  formations  lying  between  the  beds  below,  sap- 
posed  to  be  of  the  age  of  the  Chemung  group  of  New  York,  but  now  called 
Kinderhook  and  placed  in  the  Mississippian,  and  the  so-called  "Coal  Measures" 
above,  was  as  follows : 
VII.     Coal  Measures. 

VI.     Kaskaskia  limestone  or  Upper  Archimedes  limestone. 
V.     Gray,  brown  or  ferruginous  sandstone,  overlying  the  limestones  of  Alton 

and  St.  Louis. 
IV.     "St.  Louis  limestone"  or  "Concretionary  limestone." 
III.     "Arenaceous  bed." 

Warsaw  or  Second  Archimedes  limestone. 
"Magnesian  limestone." 

Beds  of  passage,  soft  shaly  or  marly  bed  with  geodes  of  quartz,  chalce- 
dony, etc. 
II.     Keokuk  limestone,  or  Lower  Archimedes  limestone. 
Beds  of  passage,  cherty  beds  60  to  100  feet. 
I.     Burlington  limestone. 

The  same  section  as  that  recorded  above  was  again  described  by  Hall3  in 
a  paper  read  before  the  Albany  Institute  in  November  1856,  although  the 
volume  was  not  published  until  1864.  In  these  papers  Hall  clearly  brought 
out  the  facts  regarding  the  geological  range  of  Archimedes,  and  showed  that 
there  were  in  truth  three  "Archimedes  limestones"  which  he  designated  as 
lower,   second,   and  upper,  but  also  applied  to  them  the  geographic  names 

iLoc.  cit.,  pt.   2,  pp.   170  and  182    (1855). 

2  Amer.  Jour.   Sci.,   2nd  ser.,  vol.   23,  p.   193;   also  Proc.  Amer.  Ass.  Adv.   Sci.,  vol.   10, 
pp.   56-57    (1857). 

3  Trans.   Albany  Inst.,  voi.   4,   pp.    2-36    (1864). 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER   GROUP  123 

Keokuk,  Warsaw,  and  Kaskaskia.     Hair's  observations  were  repeated  in  his 
final  report  for  the  Geological  Survey  of  Iowa1,  published  in  1858. 

Further  usage  of  the  name  "Archimedes  limestone"  was  made  by  Owen 
in  the  four  volumes  of  his  reports  on  the  Geological  Survey  of  Kentucky, 
published  in  1856,  1857,  and  1861,  and  also  in  his  Arkansas  reports2  published 
in  1858  and  1860.  In  every  instance  in  these  Kentucky  and  Arkansas 
reports,  as  in  his  earlier  Indiana  report,  the  rocks  so  designated  correspond 
in  stratigraphic  position  with  the  Upper  Archimedes  or  Kaskaskia  limestone 
of  Hall. 

Hall's  further  description  of  the  Kaskaskia  limestone  appears  in  his 
Iowa  report3,  where  he  described  the  formation  as  follows: 

This  rock  forms  the  cliff  bordering  the  American  bottom  from  Kaskaskia 
to  Chester,  and  thence  southward,  having  a  continuous  exposure  of  more  than 
ten  miles.  The  lower  part  is  a  compact,  arenaceous  and  coarse  textured  lime- 
stone, with  shaly  partings,  and  containing  numerous  fossils.  In  its  central  and 
upper  portions  it  includes  a  thick  bed  of  sandstone,  and  the  limestone  beds  are 
separated  by  shaly  partings  which  often  equal  the  calcareous  strata  in  thickness. 
Towards  the  higher  part  there  is  a  mass  of  green  shale  or  marl  sixty  feet  thick, 
and  this  is  again  succeeded  by  some  heavier  beds  of  limestone  containing 
Spirifer,  Allorisma,  and  a  species  of  Pinna. 

The  term  Chester  was  first  used  as  a  geologic  formation  name  by 
Swallow4  in  1858,  in  a  paper  entitled  "Explanations  of  the  Geological  Map 
of  Missouri,  and  a  Section  of  its  Bocks."  The  name  was  applied  to  a  sand- 
stone occurring  at  the  summit  of  the  "Lower  Carboniferous"  rocks.  The 
entire  Mississippian  section  described  by  Swallow,  with  the  equivalents  in 
the  more  modern  nomenclature,  is  as  follows : 

Swallow  Modern 

Feet 

Chester  sandstone 75       Palestine  sandstone 

Upper   Archimedes    limestone 250       Kaskaskia   limestone   of  Hall 

Ferruginous    sandstone 195      Aux  Vases  sandstone 

(  Ste.  Genevieve  limestone 

St.    Louis   limestone 225  J  St.  Louis  limestone 

(  Spergen  limestone 

Archimedes    limestone 350  J  Warsaw  formation 

(  Keokuk  limestone 
Encrinital   limestone 550       Burlington  limestone 

Most  of  the  thicknesses  of  the  beds  as  recorded  by  Swallow  in  this  place 
are  excessive,  some  of  them  very  much  so,  but  it  is  quite  clear  what  strati- 
graphic  units  he  had  in  mind  in  his  several  divisions.  The  Chester  sandstone 
of  Swallow  is  clearly  that  formation  which  has  been  extensively  quarried  for 
building  purposes  in  the  environs  of  Chester,  and  which  has  furnished  the 

1  Rept.  Geol.   Survey  Iowa,  vol.   1,  pt.   1,   p.    109,    (1858). 

2  First  and  Second  Repts.  Geol.  Reconn.  Arkansas,    (1858-1860) 

3  Rept.   Geol.   Surv.    Iowa,  vol.    1.  pt.   1,   r>.   107,    (1858). 
4Proc.  Amer.  Ass.  Adv.   Sci.,   vol.    11,   pt.    2,   p.    .".,    (18T.8) 


124  GEOLOGY    OF    HARDIN    COUNTY 

material  for  the  buildings  of  the  Southern  Illinois  Penitentiary  at  Menard. 
The  original  description  of  the  formation  is  as  follows:  "Sixty-five  feet  of 
heavy  bedded,  irregularly  stratified,  brownish  sandstone.  It  is  made  up  of 
round  and  angular  pellucid  particles,  having  the  interstices  filled  with  a  fine, 
opaque,  brown  substance,  which  is  often  replaced  by  oxides  of  iron  and 
manganese." 

In  Hall's  interpretation  of  the  Chester  section,  the  Chester  sandstone 
of  Swallow  was  considered  as  being  basal  "Coal  Measures,"  since  the  upper 
portion  of  his  Kaskaskia  limestone  was  said  to  be  characterized  by  Spirifer, 
Allorisma,  and  a  species  of  Pinna,  an  association  of  forms  which  clearly 
means  Menard  limestone. 

The  earliest  use  of  the  name  Chester  for  the  limestones  below  the  Chester 
sandstone  of  Swallow,  was  by  Worthen1  in  1860.  No  definition  of  the  forma- 
tion as  such,  was  given,  the  name  being  employed  simply  as  an  alternative  for 
the  Upper  Archimedes  limestone,  in  exactly  the  same  manner  as  Kaskaskia 
had  been  used  by  Hall  at  an  earlier  date. 

In  1863  Henry  Englemann2  placed  on  record  the  results  of  his  observa- 
tions upon  the  Mississippian  section  in  Johnson  and  the  adjoining  counties 
in  southern  Illinois.  The  name  Chester  limestone,  as  used  by  this  author,  is 
the  exact  equivalent  of  the  Kaskaskia  limestone  of  Hall,  and  the  Chester 
limestone  of  Worthen.  His  general  section  is  divided  into  four  members. 
"A. — Coal  Measures,  B. — Millstone-grit,  C. — A  series  of  strata  which  corre- 
spond to  the  Chester  limestone  and  Ferruginous  sandstone,  D. — St.  Louis 
limestone."  A  detailed  section  of  his  division  C,  which  is  said  to  aggregate 
a  thickness  of  1,000  feet,  is  as  follows,  the  successive  beds  being  numbered 
downward  from  the  summit: 

1.  Limestone,  generally  highly  siliceous  and  even  flinty,  and  shades,  with 

an  aggregate  thickness  of  about  180  feet. 

2.  Quartzose   sandstone,   alternating  with   shaly  beds,   and   in    some   places 

slaty  limestones  at  its  upper  part,  from  120  to  150  feet. 

3.  Limestones  and  shales  from  80  to  120  feet. 

4.  Quartzose  sandstone  with  some  beds  of  shale,  over  100  feet. 

5.  Siliceous  limestone  and  shale,  in  places  as  much  as  140  feet. 

6.  Quartzose  sandstone  and  shales,  from  60  to  100  feet  or  more. 

7.  Siliceous  limestones  and  shales,  about  150  feet. 

8.  Quartzose  sandstone,  with  some  shaly  portions,  about  150  feet  thick.     I 

have  distinguished  these  by  the  name  Cypress  sandstones  on  account 
of  their  prominent  development  on  Cypress  Creek. 

9.  Siliceous  limestone  and  shales,  the  latter  in   places  arenaceous.     These 

appear  as  beds   of  passage  between   C   and   D,   while  at  many  points 
No.  8  rests  directly  on  D. 

1  Trans,  St.  Louis  Acad.  Sci.,  vol.  1,  p.   697,    (1860)  ;  also  Proc.  Amer.  Ass.  Adv.  Sci., 
vol.   13,  pp.    312-313,    (1860). 

2  Trans.   St.  Louis  Acad.   Sci.,  vol.   2,  pt.   1,  p.  189,    (1863). 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER    GROUP  125 

10.  Locally  strata  of  sandstone  intervene  between  No.  9  and  D,  they  generally 
appear  as  an  important  bed  of  transition,  neither  thick  nor  pure,  but 
rather  an  arenaceous  development  of  the  shales  of  No.  9. 

The  first  use  of  the  name  Cypress  as  a  formation  name  occurs,  in  the 
description  of  the  section  quoted  above,  and  it  was  Engelmann's  belief  that 
"the  Cypress  sandstone,  No.  8,  may  be  regarded  as  a  more  fully  developed 
equivalent  of  the  Ferruginous  sandstone  of  the  Missouri  Geological  Report," 
an  incorrect  correlation  which  later  came  to  be  generally  adopted. 

Worthen's  description  of  the  section  at  Chester,  published  in  18661,  was 
based  upon  more  extended  field  observations  than  either  the  sections  of 
Swallow  or  of  Hall,  and  in  this  place  the  use  of  Chester  as  the  name  of  a 
group  of  beds  was  applied  for  the  first  time,  being  used  to  include  the  sand- 
stone which  had  been  designated  "Ferruginous  sandstone"  by  Hall  and  by 
Swallow,  and  the  overlying  beds  to  the  summit  of  the  "Sub-Carboniferous" 
in  the  Mississippi  River  section.  The  name  "Ferruginous  sandstone,"  how- 
ever, was  rejected  by  Worthen  in  this  place,  since  it  had  been  applied  first 
to  the  basal  sandstone  of  the  "Coal  Measures"  by  the  Missouri  geologists,  and 
the  two  sandstones,  one  Mississippian  and  the  other  Pennsylvanian,  had  been 
confused.  Worthen  proposed  the  name  "Lower  Sandstone  of  the  Chester 
Group"  for  this  division  of  the  "Sub-Carboniferous,"  and  consistently  used 
it  in  his  later  writings.  The  original  description  of  the  "Chester  group"  is 
as  follows : 

"CHESTER  GROUP" 

This  group  comprises  three  or  more  beds  of  limestone,  with  intercalated 
beds  of  arenaceous  and  argillaceous  shales  and  sandstones,  the  whole  attaining 
a  maximum  thickness  of  at  least  six  hundred  feet.  The  following  section  will 
illustrate  the  general  characters  of  this  group,  as  it  appears  in  the  county  above 
named    [Randolph],  where  its  peculiar  features  were  first  studied: 

10.     Hard  gray  siliceous   limestone 25  to  30  feet 

9.     Shales    and    shaly    sandstones,    with    fossil    plants,    Sigillaria, 

Stiffmaria,  Lepidodendron,   Knorria,   etc.    (partly  hidden) ...   80    "    90     " 

8.     Shaly   limestone    (local) 15    "    18     " 

7.     Massive    brown    sandstone 40     " 

6.     Limestone,  partly  nodular  and  argillaceous 45     " 

5.     Green  and  blue  argillaceous  shales,  with  plates  of  limestone..   45    "    70     " 

4.     Argillaceous  and  siliceous  limestone    (local).... 20    "    30     " 

3.     Massive  sandstone  and  sandy  shale 15    "    20     " 

2.     Compact  gray  limestone,  with  intercalations  of  blue,  green  and 

purple  clay  shales 150     " 

1.     Brown    sandstone 120     " 

In  his  supplementary  description  of  the  "Chester  group,"  which  is  the 
equivalent  of  Engelmann's  subdivision  C,  Worthen  refers  to  the  work  of 
Engelmann  in  the  more  southern  counties  of  the  State  with  the  statement 

1Geol.   Surv.   Illinois,  vol.  1,  p.   77,    (1866). 


126  GEOLOGY  OF  HARDIN  COUNTY 

that  the  beds  are  considerably  increased  in  thickness  in  that  direction. 
Engelmann's  county  reports  are  published  in  full  in  another  part  of  the 
volume  in  which  Worthen's  general  discussion  appears,  but  neither  Worthen 
nor  Engelmann,  in  the  final  report,  make  any  use  of  the  term  Cypress  as  a 
formation  name,  although  it  had  been  introduced  several  years  earlier. 

The  report  on  Union  County,  Illinois1,  written  by  Worthen,  appeared  in 
1868,  but  a  footnote2  states  that  it  is  "reported  in  part  from  observations  of 
Mr.  Henry  Engelmann,"  and  in  it  the  same  Chester  subdivisions  are  recog- 
nized which  were  described  at  an  earlier  date  by  Engelmann  in  his  Johnson 
County  report.  It  is  in  this  county  that  the  typical  exposures  of  the  Cypress 
sandstone  occur,  although  the  name  Cypress  is  not  used  in  the  report,  this 
sandstone  being  referred  to  in  every  case  as  No.  8.  A  careful  reading  of  the 
text  of  the  Union  and  other  county  reports,  in  connection  with  more  recent 
field  observations,  has  shown  that  three  distinct  sandstones  in  the  Chester 
group  were  confused  as  No.  8  by  these  earlier  observers.  No  occurrence  of 
beds  9  and  10  of  Engelmann's  Johnson  County  section  are  recorded  in  Union 
County,  but  in  fact  sub-Cypress  beds  are  as  fully  developed  in  this  county 
as  in  Johnson,  or  any  of  the  more  eastern  counties  of  the  state,  and  a  sub- 
Cypress  sandstone  has  been  referred  to  as  No.  8  in  a  number  of  localities 
enumerated,  in  such  sections  the  true  Cypress  being  designated  as  No.  6. 

Since  the  publication  of  these  Illinois  county  reports,  1866-1868,  no 
advance  was  made  in  the  interpretation  of  the  stratigraphy  of  the  Chester 
group  for  nearly  forty  years.  Many  species  of  Chester  or  Kaskaskia  fossils 
have  been  described,  by  many  different  authors,  but  rarely  has  any  attempt 
been  made  to  refer  them  to  closer  stratigraphic  position  than  Chester  "group' 
or  "limestone,"  or  Kaskaskia  "group"  or  "limestone,"  and  nowhere  have  any 
distinct  faunal  zones  in  the  series  been  recognized  which  might  be  of  service 
in  more  detailed  stratigraphic  work  than  had  been  attempted .  previously. 
With  the  constantly  increasing  demands,  during  recent  years,  for  greater 
refinement  in  stratigraphic  work,  it  finally  became  apparent  that  this  great 
series  of  Chester  rocks,  a  thousand  feet  or  more  in  thickness,  must  be  divided 
if  any  further  progress  in  the  interpretation  of  the  series  was  to  be  realized. 

The  first  attempt  to  break  up  the  Chester  into  subordinate  formations 
was  made  by  Ulrich3  in  1905,  in  connection  with  his  studies  in  the  fluorspar 
mining  region  of  western  Kentucky,  chiefly  in  Crittenden  and  Caldwell 
counties.  The  subdivisions  of  the  Chester  and  the  relations  of  the  forma- 
tions recognized  by  Ulrich  at  this  time  are  shown  in  the  following  table4 : 

1Geol.   Surv.  Illinois,   vol.   3,   pp.    33-57,    (1868). 

2Loc.  cit.,  p.  20. 

3U.   S.   Geol.  Surv.,   Prof.   Paper   36,    CI  905) 

4  Loc.   cit.,  p.  24. 


UPPER    MISSISSIPPI  AN    SERIES,    CHESTER   GROUP 
Ulrich's  subdivisions  of  the  Chester,  1905 


127 


o 

1.1 

CG 

Birds  ville 

formation 

Kaskaskia  limestone  of  Hall 
Chester  limestone  of  authors 
Huron  formation  of  recent  Indiana 

reports  is  same  as  Birdsville 

formation 

Tribune 

limestone 

o 

s- 

O 

02 

Cypress  sandstone 

Aux  Vases  sandstone  of  Keyes 
Probably  also  Big  Clifty  sandstone 
of  Norwood 

Ste.  Genevieve 
limestone 

'  Ohara 

limestone 
Rosiclare 

sandstone 
Fredonia 

oolitic 

limestone 

Two  upper  members  referred  to 

as  lower  Chester  by  Worthen  and 
Englemann.     Entire  formation 
referred  to  as  St.  Louis  by 
Norwood 

Ulrich's  innovations  in  this  classification  consist  in  the  inclusion  of  the 
Ste.  Genevieve  limestone  in  the  "Chester  group,"  and  the  division  of  the 
Kaskaskia  limestone  into  two  formations,  as  well  as  the  revival  of  the  name 
Cypress  for  Worthen's  "basal  sandstone  of  the  Chester  group." 

The  present  writer  entered  upon  his  studies  of  the  Chester  rocks  and 
their  faunas  in  the  summer  of  1906,  and  these  investigations  have  been  con- 
tinued to  the  present  time.  During  the  earlier  years  of  this  period  the 
studies  were  quite  general,  but  beginning  with  the  summer  of  1911  an  in- 
tensive investigation  of  the  Chester  stratigraphy  and  paleontology  has  been 
|  conducted  in  connection  with  the  detailed  mapping  of  the  areas  occupied  by 
the  rocks  of  this  age  in  southwestern  and  southern  Illinois.  Early  in  the 
progress  of  this  work  it  was  found  to  be  desirable  to  subdivide  the  Chester 
group  in  its  typical  area  in  Randolph  and  Monroe  counties,  Illinois,  into 
several  distinct  formations  as  follows1  : 

9.     Clore  limestone 

8.     Palestine  sandstone 

7.     Menard  limestone 

6.     Okaw  limestone 

5.     Ruma  formation 

4.     Paint  Creek  formation 

3.     Yankeetown  formation 

2.     Renault  formation 

1.     Brew'erville  sandstone  (later  referred 
to  Aux  Vases  sandstone) 


1  Trans.  Illinois  Acad.  Sci.,  vol.  6,  pp.  118-129,    (1913)  ;   also  Illinois  State  Geol.   Surv. 
Monog-.   I,  pp.   23-29,    (1914). 


128 


GEOLOGY  OF  HARDIN  COUNTY 


During  the  progress  of  this  work  a  diligent  effort  was  made  to  interpret 
the  Illinois  section  in  the  light  of  Ulrich's  description  of  the  western  Ken- 
tucky Chester.  The  basal  sandstone  of  the  group  was  considered  as  being 
the  equivalent  of  the  "Cypress  sandstone"  of  southwestern  Illinois  and 
Kentucky,  Engelmann  and  Worthen  as  well  as  Ulrich  being  followed  in  this 
respect.  If  this  correlation  were  the  correct  one,  and  if  the  two  sections  were 
equivalent,  then  the  formation  next  above  this  sandstone  would  be  correlated 
with  the  Tribune  limestone  of  Ulrich's  classification.  However,  the  portion 
of  the  southwestern  Illinois  section  which  seemed  to  agree  most  closely  with 
Ulrich's  description  of  his  Tribune  limestone  was  a  lower  member  of  the 
Okaw  formation  which  contains  much  oolite  and  is  characterized  by  a  fauna 
which  consists  largely  of  diminutive  mollusca.  With  such  a  correlation  the 
Renault,  Yankeetown,  Paint  Creek,  and  Ruma  formations  would  seem  to 
have  no  equivalents  in  the  Kentucky  section.  If  the  Okaw  or  some  con- 
siderable portion  of  the  lower  part  of  that  formation  was  to  be  correlated  with 
the  Tribune,  then  the  formations  above  the  Okaw  with  perhaps  some  of  the 
upper  portion  of  the  Okaw  itself,  would  represent  the  Birdsville  formation. 
When  all  sides  of  the  question  were  considered  there  seemed  to  be  many 
inconsistencies  in  any  such  correlation  as  that  suggested.  Looked  at  in 
one  way  the  lower  Okaw  seemed  to  be  Tribune,  looked  at  in  another  way  it' 
seemed  as  though  all  the  Okaw  should  be  Birdsville.  After  careful  considera- 
tion of  the  whole  question  the  decision  was  reached  that  it  was  not  possible 
to  fit  the  western  Illinois  Chester  section  into  Ulrich's  classification  of  the 
group  in  Kentucky. 

Ulrich's  own  early  interpretation  of  the  western  Illinois  section  was  an 
impossible  one.  In  a  communication  dated  Nov.  18th,  1911,  he  made  the 
following  statement  "Regarding  your  contention  that  the  Birdsville  is  a 
synonym  of  Kaskaskia  I  am  convinced  of  its  error.  The  latter  includes  the 
Tribune,  which  formation  indeed  constitutes  the  lower  and  most  important  of 
the  limestones  comprised  under  the  term  Kaskaskia  along  the  Mississippi. 
The  Birdsville,  on  the  contrary,  follows  the  Tribune  and  begins  locally,  as 
north  of  St.  Marys,  with  a  conglomerate  containing  pebbles  of  igneous  rocks." 
In  this  interpretation  by  Ulrich  the  Tribune  included  the  major  portion  of 
Okaw  limestone.  Later  observations  proved  that  the  conglomerate  near 
St.  Marys,  which  he  had  considered  as  marking  the  base  of  the  Birdsville  is 
situated  at  the  base  of  the  Renault  formation  and  lies  immediately  on  top 
of  the  Aux  Vases  sandstone,  the  basal  sandstone  of  the  group,  its  stratigraphic 
position  being  at  least  300  feet  beneath  the  limestone  at  Chester  which  he 
had  identified  as  Tribune.  It  is  needless  to  say  that  Mr.  Ulrich  has  recog- 
nized his  error  in  this  correlation,  and  his  present  interpretation  is  a  totally 
different  one. 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER   GROUP  129 

The  differences  of  opinion  between  Ulrich  and  the  present  writer  con- 
cerning the  interpretation  of  the  Chester  sections,  led  to  the  planning  of  a 
field  conference  in  the  summer  of  1913.  This  conference  was  participated  in 
by  Messrs.  Ulrich,  DeWolf,  Buehler  and  the  writer.  A  week  was  spent  in 
hasty  visits  to  localities  in  Illinois,  Missouri,  and  Kentucky,  but  no  agreement 
was  reached  concerning  the  questions  at  issue.  During  the  seasons  following 
this  conference  the  detailed  studies  and  mapping  of  the  Chester  have  been 
continued,  and  the  work  has  been  carried  into  the  more  southern  counties  of 
Illinois,  Hardin,  Pope,  and  Johnson,  which  adjoin  that  portion  of  Kentucky 
in  which  Ulrich  did  his  work. 

Upon  entering  on  the  intensive  study  of  the  Chester  group  in  these 
southern  counties  of  Illinois  in  1915,  nearly  one  entire  season  was  devoted 
to  reconnaissance  work  in  Illinois  and  in  the  adjoining  portion  of  Kentucky, 
including  Crittenden  and  Caldwell  counties,  which  is  the  heart  of  the  region 
in  which  Ulrich  prosecuted  his  studies  more  than  25  years  ago.  A  second 
field  conference  between  Messrs.  Girty  and  Butts  of  the  U.  S.  Geological 
Survey,  and  the  writer,  occurred  during  this  season,  at  which  time  Butts 
received  his  first  introduction  to  the  Chester  of  the  Ohio  and  Mississippi 
valleys.  The  work  of  this  season  brought  to  light  a  number  of  serious  mis- 
takes that  had  been  made  by  Ulrich  in  his  earlier  work.  In  the  first  place  the 
limestone  at  Tribune,  Kentucky,  supposedly  the  type  locality  for  the  formation 
of  that  name,  was  found  to  occupy  a  position  far  up  in  the  Birdsville  forma- 
tion, being  indeed  the  southeastern  extension  of  the  Menard  limestone  of  the 
writer,  named  from  Eandolph  County,  Illinois.  It  very  soon  became  evident 
that  Ulrich  had  included  in  his  Tribune  limestone,  and  had  so  mapped,  lime- 
stones occupying  three  distinct  horizons  in  the  Chester  series.  The  Tribune 
limestone  at  Tribune  was  found  to  be  well  up  in  the  Birdsville  formation  as 
that  member  had  been  defined.  The  Tribune  east  of  Princeton,  Kentucky, 
lies  above  the  sandstone  that  had  been  mistakenly  identified  as  Cypress  by 
Ulrich,  this  being  the  position  assigned  to  the  formation  by  him  in  the 
stratigraphic  sequence  of  the  Chester.  The  third  limestone  referred  to  the 
Tribune  was  that  at  the  mouth  of  the  Fairview  mine  at  Rosiclare,  Illinois, 
which  proved  to  have  a  position  beneath  the  sandstone  which  Ulrich  had  called 
Cypress,  being  in  fact,  the  upper  part  of  the  limestone  he  had  elsewhere  called 
the  Ohara  member  of  the  S-te.  Genevieve  limestone.  It  was  also  recognized 
during  this  season  that  Ulrich  was  mistaken  in  his  interpretation  of  the 
Cypress  sandstone  of  Engelmann,  the  true  Cypress  being  at  the  base  of 
the  Birdsville  formation  instead  of  beneath  the  so-called  Tribune. 

The  most  serious  of  Ulrich's  mistakes  was  found  to  be  in  his  location 
of  the  basal  boundary  of  the  Chester  group.  He  included  the  Ste.  Genevieve 
limestones  in  the  Chester,  drawing  the  lower  boundary  of  the  group  between 
—9  G 


130  GEOLOGY    OF   HARDIN    COUNTY 

the  St.  Louis  and  the  Ste.  Genevieve  limestones.  It  was  found  that  the 
upper  member  of  the  Ste.  Genevieve  of  Ulrich,  the  Ohara  limestone,  included 
two  distinct  units,  the  lower  one  truly  Ste.  Genevieve  in  age,  and  the  upper 
one  characteristically  Chester,  and  a  later  very  careful  study  of  the  faunas 
in  the  laboratory  showed  that  the  upper  division  of  the  Ohara  was  the  exact 
correlate  of  the  Renault  limestone  of  the  Randolph  County  section.  This 
two-fold  division  of  the  Ohara  was  further  established  by  the  recognition  of 
a  distinct  line  of  unconformity  in  the  midst  of  the  limestone.  At  a  number 
of  places  this  stratigraphic  break  is  marked  by  the  presence  of  a  basal  con- 
glomerate in  the  higher  bed,  and  elsewhere  by  other  indisputable  evidences 
of  unconformity.  Most  diligent  search  at  every  locality  where  the  Ohara 
limestone  has  been  met  has  been  made  by  the  writer  for  the  characteristic  Ste. 
Genevieve  fossils  in  the  "Upper  Ohara"  limestone,  and  not  a  single  such 
occurrence  has  been  detected  during  five  field  seasons.  Ulrich  has  claimed 
to  have  collected  such  typical  Ste.  Genevieve  species  as  PJatycrinus  penicillus 
in  the  "Upper  Ohara,"  and  he  has  always  referred,  in  the  course  of  discussion, 
to  a  locality  near  Levias,  Crittenden  County,  Kentucky.  This  locality  was 
visited  by  the  writer  during  the  past  season  (1918)  in  company  with  Mr. 
Chas.  Butts,  and  it  was  established  that  the  sandstone  identified  and  mapped 
by  Ulrich  at  this  locality  as  Cypress,  was  really  Rosiclare,  and  consequently 
his  supposed  "Upper  Ohara"  fossils  were  actually  collected  from  the  Fredonia 
limestone,  where  they  really  belong. 

Since  his  introduction  to  the  subject,  Butts  has  continued  his  studies 
on  the  Chester.  He  soon  discovered,  during  his  examination  of  the  section 
in  Kentucky,  that  a  cherty  limestone  member  that  Ulrich  had  described  as 
being  included  in  the  Cypress  sandstone,  was  in  fact  the  upper  portion  of 
the  Ohara  limestone.  With  this  mistake  in  interpretation  it  is  seen  that 
Ulrich  has  identified  the  "Upper  Ohara"  in  three  different  localities,  as 
three  different  units.  At  Cedar  Bluff,  near  Princeton,  Kentucky,  the  type 
locality  for  the  Ohara,  he  placed  it  where  it  properly  belongs.  At  a  number 
of  Kentucky  localities  he  considered  it  as  a  limestone  member  of  the  Cypress, 
and  at  the  mouth  of  the  Fairview  mine  at  Rosiclare,  he  identified  it  as 
Tribune  limestone. 

Butts'  most  important  contribution  to  our  knowledge  of  the  Chester 
section  in  southeastern  Illinois,  was  the  recognition,  for  the  first  time,  of 
an  important  shale  formation  lying  between  the  sandstone  Ulrich  had  erro- 
neously called  Cypress  and  the  true  Cypress  of  Engelmann.  This  shale 
contains  some  limestone  layers,  and  on  being  traced  westward  into  Johnson 
County  is  found  to  be  the  equivalent  of  the  Paint  Creek  formation  of  Ran- 
dolph and  Monroe  counties.  Extending  southward  into  Kentucky  the  same 
unit  is  represented  by  at  least  some  portion  of  the  formation  having  the 
stratigraphic  position  assigned  to  the  Tribune  limestone  by  Ulrich,  a  for- 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER    GROUP  131 

mation  which  has  more  recently  been  called  Gasper  by  Butts  because  of  the 
unfortunate  choice  of  the  name  Tribune  by  Ulrich. 

During  the  progress  of  these  recent  studies  on  the  Chester,  the  writer's 
results  have  been  recorded  in  manuscript  from  time  to  time,  and  copies  of 
all  but  one  of  these  manuscripts  have  been  transmitted  to  Ulrich.  Most 
of  the  mistakes  in  his  earlier  work  that  have  been  pointed  out  to  him,  have 
been  acknowledged  by  Ulrich,  but  he  has  been  willing  to  make  no  compro- 
mise in  regard  to  his  interpretation  of  the  Ste.  Genevieve.  He  has  continued 
to  insist  that  the  Ohara  member  is  not  divisible,  and  that  the  whole  of  the 
Ste.  Genevieve  formation  is  properly  a  member  of  the  Chester  group. 

A  final  field  conference  was  arranged  in  the  summer  of  1916,  partici- 
pated in  by  Messrs.  Ulrich,  Butts,  Girty,  and  Ashley,  of  the  U.  S.  Geolog- 
ical Survey,  with  DeWolf  and  the  writer.  Nearly  two  weeks  were  spent  in 
Illinois,  Missouri,  and  Kentucky.  In  the  course  of  this  conference  the 
present  writer's  interpretation  of  the  critical  section  in  the  Ohio  Eiver  bluff 
below  Eosiclare  was  completely  accepted  by  Ulrich.  It  was  agreed  that 
the  "Upper  Ohara"  of  this  section  was  the  equivalent  of  the  Kenault  lime- 
stone of  Randolph  County,  and  that  there  was  a  distinct  unconformity  here 
separating  the  Renault  from  the  underlying  St.  Genevieve  limestone.  A 
few  days  later,  on  visiting  the  type  locality  of  the  Ohara  limestone  near 
Princeton,  Kentucky,  the  writer  insisted  that  the  section  was  the  same  as 
that  below  Eosiclare,  but  this  was  disputed  by  Ulrich.  Later  in  the  same 
season,  however,  Butts  actually  traced  the  beds  across  country  from  the  Eosi- 
clare locality  to  Princeton  and  demonstrated  that  the  sections  were  the  same. 

Early  in  1918  a  volume  was  issued  by  the  Kentucky  Geological  Survey, 
entitled  "Mississippian  Formation  of  Western  Kentucky."  It  contains  two 
papers,  the  first  by  Chas.  Butts  on  "Descriptions  and  correlation  of  the 
Mississippian  formations  of  western  Kentucky,"  and  the  second  by  E.  0. 
Ulrich  on  "The  Formations  of  the  Cnester  series  in  western  Kentucky  and 
their  correlates  elsewhere".  This  contribution  by  Ulrich  is  essentially  a 
revision  of  his  earlier  work  published  in  Professional  Paper  No.  36,  of  the 
U.  S.  Geological  Survey.  A  number  of  the  mistakes  of  the  earlier  report 
are  acknowledged  and  corrected.  Some  of  his  earlier  fallacies  are  adhered 
to  and  at  least  one  new  error  of  importance  is  fallen  into.  The  work  is 
controversial  from  beginning  to  end,  and  is  an  attempt  to  establish  his 
own  interpretation  as  opposed  to  that  of  the  writer,  expressed  in  the  several 
manuscript  reports  which  had  been  furnished  him.  The  one  new  mistake 
of  Ulrich,  mentioned  above,  is  in  the  correlation  of  the  Cypress  sandstone 
with  the  Lower  Okaw  limestone  of  the  Randolph  County  section.  The 
results  of  the  writer's  studies  in  Johnson  County,  Illinois,  establish  without 
doubt,  the  equivalence  of  the  Golconda  limestone  of  southeastern  Illinois 
with  the  Lower  Okaw,  the  evidence  for  which  will  be  presented  later. 


132 


GEOLOGY  OF  HARDIN  COUNTY 


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UPPER   MISSISSIPPIAN   SERIES,    CHESTER   GROUP  133 

In  the  following  pages  the  several  Chester  formations  of  southeastern 
Illinois,  especially  as  exhibited  in  Hardin  Comity,  will  be  described  and 
discussed,  and  the  evidence  for  the  conclusions  that  have  been  reached,  will 
be  presented. 

Shetlerville  Formation 

name  and  general  distribution 

The  Shetlerville  formation  is  here  named  and  denned  for  the  first  time, 
it  is  a  constituent  part  of  the  upper  limestone  or  Ohara  member  of  the 
Ste.  Genevieve  formation  as  redefined  by  Ulrich1,  but  the  field  studies  of 
the  past  few  years  have  shown  that  this  Ohara  limestone  is  a  complex  unit 
which  must  be  broken  up  in  order  to  properly  display  the  true  relations 
of  the  stratigraphic  succession  in  southeastern  Illinois  and  the  adjacent 
portion  of  Kentucky.  The  "Upper  Ohara"  is  entirely  foreign  to  any  por- 
tion of  the  true  Ste.  Genevieve  limestone  as  that  formation  is  typically 
developed  in  Ste.  Genevieve  County,  Missouri,  and  in  Hardin  County  and  the 
adjacent  areas  it  is  separated  from  the  "Lower  Ohara,"  which  is  a  part 
of  the   Ste.   Genevieve  formation,  by   a   distinct   unconformity. 

It  is  the  basal  portion  of  the  "Upper  Ohara"  that  is  here  designated 
as  the  Shetlerville  formation,  from  its  excellent  exposures  just  east  of 
Shetlerville,  between  that  place  and  Eich  and  Melcher  hills.  The  formation 
is  well  exposed  at  a  number  of  localities  in  Hardin  County,  and  in  a  few 
localities  in  the  neighboring  Pope  County.  Outside  of  this  area  it  occurs 
at  numerous  localities  in  the  adjacent  portion  of  Kentucky,  more  especially 
Crittenden  County,  but  it  is  known  to  extend  also  into  Caldwell  County. 
The  formation  is  also  believed  to  be  present  as  far  west  as  Union  County, 
Illinois. 

In  mapping  the  geology  of  Hardin  County  it  has  not  been  practicable 
to  separate  the  Shelterville  from  the  overlying  Eenault,  so  the  two  forma- 
tions are  included  under  the  same  color.  The  Shetlerville  is  more  or  less 
completely  talus-covered  in  many  localities  where  it  might  be  looked  for, 
but  aside  from  the  already  mentioned  locality  east  of  Shetlerville,  the  for- 
mation is  well  exposed  south  of  Eichorn,  and  in  Downeys  and  Fairview  bluffs 
below  Eosiclare.  It  also  may  be  looked  for  in  the  hills  east  of  Wallace 
Branch,  about  two  miles  from  the  mouth  of  that  stream,  and  in  the  hill 
southeast  of  the  mouth  of  Hogthief  Creek,  three  and  one-half  miles  north- 
west of  Elizabethtown,  although  no  outcrops  have  yet  been  detected  in 
either  of  these  localities.  In  belt  number  three  of  the  faulted  portion  of  the 
county  (see  figure  3)  the  Shetlerville  is  exposed  in  at  least  one  locality  north- 
west of  Peters  Creek,  In  the  southeastern  non-faulted  portion  of  the  county, 
the  formation  should  be  present  beneath  the  Eenault  in  the  belt  extending  from 

1U.   S.   Geol.   Survey,  Prof.  Paper  No.   36,  p.   39,    (1905). 


134  3E0L0GY    OF    HARDIN    COUNTY 

the  Peters  Creek  fault  to  the  Ohio  Kiver  bluffs ;  and  at  one  point,  in  the  fields 
southwest  of  the  road  intersection  two  and  one-half  miles  north  of  Cave  in 
Rock,  the  formation  is  exposed  in  sec.  1,  T.  12  S.,  R.  9  E. 

From  the  wide  distribution  of  known  exposures  of  the  Shetlerville,  it 
may  be  safely  assumed  to  be  uniformly  present  in  Hardin  County  wherever 
the  proper  part  of  the  geological  section  forms  the  surface  rocks,  although 
it  is  commonly  hidden  from  view  by  the  surficial  covering. 

LITIIOLOGIC    CHARACTER 

In  its  lithologic  character  the  Shetlerville  formation  is  in  strong  con- 
trast with  the  subjacent  Ste.  Genevieve  limestone,  in  that  it  is  much  more 
shaly,  much  more  irregularly  bedded  and  much  less  uniform  in  character. 
The  limestone  beds  of  the  formation  are  commonly  crystalline  in  character, 
and  are  dark  gray  or  blue  gray  in  color,  and  when  well  exposed  they  exhibit 
more  or  less  well  pronounced  cross-bedding  in  most  localities.  The  lime- 
stones are  interbedded  with  more  or  less  calcareous  shales,  but  the  lime- 
stonestone  and  shale  succession  is  not  uniform  from  place  to  place,  and  the 
limestone  layers  are  seen  to  grade  into  shales  horizontally.  In  places  the 
limestone  may  constitute  nearly  the  entire  formation,  the  shale  content  being 
reduced  to  little  more  than  partings  between  the  limestone  ledges;  elsewhere 
the  shales  may  constitute  the  greater  part  of  the  formation.  Where  shales 
predominate  the  limestone  not  infrequently  occurs  as  plate-like,  discon- 
tinuous layers  an  inch  or  thereabouts  in  thickness,  which  are  composed  for 
the  most  part  of  fragments  of  fossils,  and  whose  weathered  surfaces  exhibit 
many  well  preserved  fossils.  Upon  the  weathered  outcrops,  the  shales  of  the 
Shetlerville  formation  are  commonly  yellowish,  buff  colored,  oi  ashy  gray, 
but  in  the  unweathered  condition  they  are  doubtless  of  a  blue  color  for  the 
most  part.  Thin  layers  of  red  shale  occur  in  places.  The  weathered  sur- 
faces of  the  limestones  are  commonly  a  yellowish  or  buff  color. 

THICKNESS 

Because  of  the  usual  covering  of  the  Shetlerville  formation  with  sur- 
ficial material,  the  actual  thickness  of  the  formation  can  be  accurately  ob- 
served in  but  few  localities.  By  far  the  best  section  for  the  accurate  de- 
termination of  the  thickness  is  in  the  northeastern  of  the  two  hills  between 
Ivosiclare  and  the  Fairview  incline,  where  both  the  lower  and  the  upper 
contacts  of  the  formation  can  be  accurately  ol (served.  At  this  point  the 
actual  thickness  is  30  feet.  It  is  not  unlikely  that  the  thickness  may  vary 
somewhat  from  place  to  place,  but  it  is  nowhere  a  thick  formation,  and  the 
observed  thickness  below  Rosiclaire  mav  be  safely  assumed  to  be  near  the 
average. 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  135 

STRATIGRAPHIC  RELATIONS 

It  has  already  been  pointed  out  that  the  Shetlerville  formation  rests 
unconformably  upon  the  underlying  Ste.  Genevieve  limestone.  This  un- 
conformity is  well  exhibited  in  the  Ohio  Eiver  bluff  above  the  railway 
incline  at  Fairview  (fig.  9),  just  below  Rosiclare,  and  it  is  again  shown 
in  the  locality  just  east  of  Shelterville.  At  this  last  locality  the  lower 
portion  of  the  formation  includes  conglomeratic  layers,  the  included  pebbles 
all  being  limestone.  Outside  the  Hardin  County  area  the  base  of  the 
Shetlerville  is  seen  to  rest  unconformably  upon  the  underlying  Ste.  Gene- 
vieve in  the  Cedar  Bluff  quarry,  near  Princeton,  Kentucky,  the  original 
type  locality  of  the  Ohara  limestone  of  Ulrich.     In  the  section  at  this  lo- 


:*zm    m0c        ,\  up 

•  *  -*^rr"  „  j*^  •  A,*Si«WHe5»^  •  :  -  - 

m                  fSt    -            -V"'           *-i    1'             -i 

Fig.  9. — View  showing  the  unconformity  between  the  Shetlerville  and  the 
underlying  Ste.  Genevieve.  The  dense,  compact  bed  in  the  lower  part  of  the 
picture  is  "Lower  Ohara"  limestone;  the  overlying,  thinly-bedded,  shaly  zone  is 
the  base  of  the  Shetlerville.  At  the  old  quarry  face  above  the  railroad  track  at 
Fairview  bluff,  below  Rosiclare,   looking  northwest. 

cality  the  base  of  the  Shetlerville  is  marked  by  a  distinct  limestone  con- 
glomerate a  foot  or  more  in  thickness,  with  pebbles  ranging  in  size  from 
two  inches  down,  the  basal  contact  of  the  conglomerate  being  the  upper  limit 
of  the  very  characteristic  Ste.  Genevieve  limestone  fauna.  At  every  locality 
where  the  actual  basal  contact  of  the  Shetlerville  has  been  observed,  there 
are  unmistakable  evidences  of  unconformity,  and  it  is  safe  to  assume  that 
this  relation  is   general. 

The  upper  contact  of  the  Shetlerville  formation  has  been  observed  in 
fewer  sections  than  has  the  basal  contact.  In  the  northeastern  of  the  two 
hills  between  Rosiclare  and  Fairview  what  may  be  the  line  of  demarcation 


136 


GEOLOGY    OF    HARDIN    COUNTY 


between  this  formation  and  the  superjacent  Eenanlt  is  very  sharp  and 
uneven  (see  figure  10),  clearly  indicating  an  uncomformable  relation  be- 
tween the  two  beds,  with  an  erosion  interval  intervening  between  the  two 
periods  of  sedimentation.  Although  this  contact  is  obscured  in  all  other 
sections  which  have  been  observed,  the  fact  that  the  seeming  unconformity 
is  so  pronounced  at  one  locality  suggests  that  it  may  be  general,  although 
no  proof  exists  that  this  may  be  more  than  a  local  phenomenon. 

PALEONTOLOGY 

The  Shetlerville  formation  is  one  of  the  most  fossiliferous  zones  in  the 
entire   Chester  group   in   Hardin   County.     In   places   where   the   shale   and 


Fig.  10. — View  showing  the  possible  unconformity  between  the  Shetlerville 
and  the  overlying  Renault  limestone,  in  the  Ohio  River  bluff  a  third  of  a  mile 
below  Rosiclare,  looking  northwest. 


limestone  beds  of  the  formation  are  exposed  in  open  glades  upon  some  of 
the  hill  slopes,  well-preserved,  clean  fossils  may  be  collected  in  quantity. 
The  larger  number  of  the  fossils  met  with  belong  to  a  comparatively  few 
species,  but  associated  with  these  abundant  or  common  forms  there  are 
many  others  which  are  more  or  less  rare  in  their  occurrence.  A  combined 
list  of  the  species  from  eight  different  localities  in  Hardin  County,  Illinois, 
and  Crittenden  County,  Kentucky,  from  which  fairly  complete  collections 
have  been  secured,  includes  69  species.  The  combined  list  is  given  below, 
the  occurrence  of  the  species  being  indicated  by  crosses  in  the  eight  columns 
numbered  1  to  8  for  the  several  localities.  The  localities  from  which  the 
collections  are  recorded  are  as  follows: 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER   GROUP 


137 


1.  Ohio  Eiver  bluff  above  the  railway  incline  of  the  Fairview  mine, 
below  Kosiclare  (Bed  No.  14,  in  section  recorded  on  page  113). 

2.  Ravine  just  east  of  Shetlerville. 

3.  Public  highway  at  southwest  corner  of  Melcher  Hills,  between  Shet- 
lerville and  Wallace  Branch. 

4.  Southern  slope  of  hill  three-fourths  of  a  mile  south  of  Eichorn. 

5.  One  mile  northwest  of  Peters  Creek  Store,  NE.  *4  sec.  7,  T.  12  S.? 
R.  8  E. 

6.  Lemon  quarry,  three  miles  west  of  Marion,  Kentucky. 

7.  Thomas   Glade,   near   Bethel    School,   four   miles   west   of   Marion, 
Crittenden  County,  Kentucky. 

8.  Moore   Glade,   four  miles  west   of   Marion,   Kentucky. 

Fossils  from  the  Shetlerville  formation  collected  in  Hardin  County,  Illinois,  and 

Crittenden  County,  Kentucky 


FOSSILS 


Triplophyllum  spinulosum  (M.-E.  and  H.) 

Amplexus  geniculates  Worthen 

Cornulites  sp 

Spirorbis  sp 

Eupachycrinus  sp 

Globocrinus  unionensis  (Worthen) 

Dichocrinus  girtyi  n.  sp 

Dichocrinus  sp 

Talarocrinus  buttsi  Ulrich 

Talarocrinus  trijugis  M.  and  G 

Crinoid  stems  and  plates 

Pentremites  pinguis  Ulrich 

Pentremites  princetonensis  Ulrich 

Pentremites  pulchellus  Ulrich 

Pentremites  tuscumbiae  Ulrich 

Mesoblastus  glaber  (M.  and  W.) 

Ascodictyon  sp 

Hederella  sp 

Fistulipora  excelens  Ulrich 

Eridopora  punctifera  Ulrich 

Stenopora  tuberculata  (Prout) 

Stenopora  cestriensis  Ulrich 

Stenopora  montif era  Ulrich 

Stenopora  sp 

Batostomella  ?  sp 

Anisotrypa  ?  sp 

Fenestella  cestriensis  Ulrich 

Fenestella  elevatipora  Ulrich 


X 


X 


X 


138 


GEOLOGY    OF    HAEDIN    COUNTY 


Fossils  from  the  Shetlerville  formation  collected  in  Hardin  County,  Illinois,  and 
Crittenden  County  Kentucky — Concluded 


FOSSILS 


1 

2 

3 

4 

5 

6 

7 

Fenestella  serratula  Ulrich 

Fenestella  tenax  Ulrich 

Archimedes  sp 

Polypora  cestriensis  Ulrich 

Polypora  spinulif era  Ulrich 

Lyropora  quincuncialis  Ulrich 

Thamniscus  furcillatus  Ulrich 

Thamniscus  ramulosus  Ulrich 

Septopora  subquadrans  Ulrich 

Rhombopora  sp 

Streblotrypa  nicklesi  Ulrich 

Cystodictya  labiosa  n.  sp 

Glyptopora  punctipora  Ulrich 

Phractopora  sp 

Crania  chesterensis  M.  and  G 

Orthotetes  kaskaskiensis  (McChesney) 

Productus  ovatus  Hall 

Productus  cf .  inflatus  McChesney .... 

Productus  sp 

Diaphragmus  elegans  (N.  and  P.) .  .  .  . 

Girtyella  indianensis  (Girty) 

Girtyella  brevilobata  (Swallow) 

Dielasma  illinoisensis  Weller 

Spiriferina  transversa  (McChesney) .  .  . 

Spiriferina  subspinosa  n.  sp 

Cyrtina  ??  sp 


Spirif  er  breckenridgensis  Weller 

Spirifer  leidyi  N.  and  P 

Spirif  er  increbescens  Hall  var 

Reticularia  setigera  (Hall) 

Eumetria  vera  (Hall) 

Eumetria  costata  (Hall) 

Cliothyridina  sublamellosa  (Hall) 

Composita  trinuclea  (Hall) 

Myalina  sp 

Allorisma  sp 

Bellerophon  sp 

Pleurotomaria  ?  sp 

Pleurotomaria  ?  sp 

Holopea  ?  sp 

Orthonychia  cf.  chesterensis  M.  and  W. 

Conularia  sp 

Orthoceras  sp 

Phillipsia  sp 


X 


X 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  139 

Of  this  list  of  72  species  eight  only  are  recorded  from  all  of  the  locali- 
ties, these  eight  species  being  as  follows: 

Amplexus  geniculates  Spiriferina   transversa 

Stenopora  tuberculata  Spiriferina  subspinosa 

Fenestella  cestriensis  Cliothyridina  sublamellosa 

Fenestella  serratula  Composita   trinuciea 

Most  of  these  species  are  long-ranging  forms,  and  all  but  Amplexus 
geniculatus,  Fenestella  cestriensis,  and  Spiriferina  subspinosa  are  known 
from  both  older  and  younger  Mississippian  faunas.  Of  these  three  Fenes- 
tella cestriensis  is  widely  represented  in  the  Chester  formations.  Amplexus 
geniculatus  and  Spiriferina  subspinosa  of  these  eight  species  are  wholly 
restricted,  so  far  as  known,  to  the  Shelterville ;  and  since  they  are  present 
in  all  of  the  localities  recorded  they  constitute  good  index  fossils  and  this 
particular  faunal  zone  may  be  known  as  the  Amplexus  geniculatus  zone. 
Two  other  species  of  the  fauna,  much  less  commonly  met  with,  which  are 
not  known  outside  of  this  zone,  are  Globocrinus  unionensis,  and  Talaro- 
crinus   buttsi. 

Eleven  of  the  recorded  species  have  been  recognized  in  seven,  or  all 
but  one  of  the  localities,  these  species  being  as  follows : 

Triplopbyllum  spinulosum  Diaphragmus  elegans 

Pentremites   princetonensis  Girtyella  indianensis 

Eridopora   punctifera  Dielasma  illinoisensis 

Fenestella   tenax  Reticularia  setigera 

Cystodictya  labiosa  Eumetria  vera 

Glyptopora  punctipora 

Four  other  species  occur  in  all  but  two,  or  in  six  of  the  localities,  these 
species  being  as  follows : 

Mesoblastus  glaber  Septopora  subquadrans 

Fistulipora   excelens  Spirifer  ieidyi 

The  25  species  enumerated  above  can  be  fairly  considered  as  consti- 
tuting the  most  important  elements  in  the  fauna  of  the  Shelterville  forma- 
tion. Of  these  species  Cliothyridina  sublamellosa  is  the  most  abundant 
form  in  every  locality,  and  in  many  places  where  large  collections  have  been 
made,  the  examples  of  this  species  constitute  a  bulk  as.  great  as  all  others 
together.  Composita  trinuciea  is  another  abundant  form,  but  it  has  nowhere 
been  observed  to  be  as  numerous  as  the  specimens  of  Cliothyridina.  The  ex- 
amples of  Pentremites  princetonensis  are  also  very  abundant  in  most  locali- 
ties, although  this  species,  as  well  as  all  other  blastoids,  is  strangely  lacking 
in  the  collection  from  Lemon  quarry,  near  Marion,  Kentucky. 

In  a  consideration  of  the  fauna  of  the  Shetlerville  formation  it  is  im- 
portant to  make  comparisons  with  the  fauna  of  the  preceding  Ste.  Genevieve 
limestone.  The  Ste.  Genevieve  is  particularly  characterized  by  Plahjcrinus 
penicillus  and  Pugnoides  ottumwa,  neither  of  which  has  been  observed  in  the 


140 


GEOLOGY    OF    HA11DIN    COUNTY 


Shetlerville  at  any  locality.  Other  species  which  are  of  common  occurrence 
in  the  Ste.  Genevieve  and  absent  from  the  Shetlerville,  are  Rhipidomella 
dubia  and  Dizygocrinus  persculptus,  an  example  of  which  was  figured  by 
Worthen  as  Batocrinus  unionensis,  but  which  is  specifically  and  generically 
distinct  from  the  type  of  that  species. 

In  the  following  table  those  members  of  the  Shetlerville  fauna  which 
have  been  specifically  identified,  have  been  recorded  with  their  geologic  range, 
the  range  in  formations  older  than  the  Shetlerville  being  shown  on  the  left, 
and  in  younger  formations  on  the  right.  In  column  1,  occurrences  in  any 
pre-Ste.  Genevieve  formation  is  recorded;  in  column  2,  Ste.  Genevieve;  in 
column  3,  Renault;  and  in  column  4,  post-Eenault.  Where  the  specific  identi- 
ties in  these  several  formations  are  the  same  the  record  in  the  proper  column 
is  indicated  by  X,  but  where  the  species  is  represented  by  a  closely  allied 
form,  but  one  not  specifically  identical,  it  is  indicated  by  0. 

Table  showing  geologic  range  of  the  Shetlerville  fauna 


SHETLERVILLE  FAUNA 


X 


X 


X 


Triplophyllum  spinulosum. 

Amplexus  geniculates 

Globocrinus  unionensis.  .  .  . 

Talarocrinus  buttsi 

Talarocrinus  trijugis 

Pentremites  princetonensis 
Pentremites  pulchellus 
Pentremites  tuscumbiae .  .  . 

Pentremites  pinguis 

Mesoblastus  glaber 

Fistulipora  excelens 

Eridopora  punctifera 

Stenopora  tuberculata .  .  .  . 

Stenopora  cestriensis 

Stenopora  montifera 

Fenestella  cestriensis 

Fenestella  elevatipora 

Fenestella  serratula 

Fenestella  tenax 

Polypora   cestriensis 

Polypora  spinulif era 

Thamniscus  furcillatus 
Thamniscus  ramulosus 
Septopora  subquadrans  .  .  . 

Streblotrypa  nicklesi 

Cystodictya  labiosa 


X 


X 


X 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER   GROUP  141 

Table  shoiving  geologic  range  of  the  Shetlerville  fauna — Concluded 


SHETLERVILLE  FAUNA 


Glyptopora  punctipora.  .  .  . 

Crania  chesterensis 

Orthotetes  kaskaskiensis .  . 

Productus  ovatus 

Diaphragmus  elegans 

Girtyella  indianensis 

'Girtyella  brevilobata 

Dielasma  illinoisensis 

Spiriferina  transversa 

Spirifer  breckenridgensis .  . 

Spirif  er  leidyi 

Spirifer  increbescens  var .  . 

Reticularia  setigera 

Eumetria  vera 

Eumetria  costata 

Cliothyridina  sublamellosa 
Composita  trinuclea 


X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

The  fauna  of  the  Shetlerville  horizon  is  that  of  the  so-called  Zone  3  of 
the  Ohara  limestone  as  recorded  by  Ulrich1,  and  the  faunal  evidence  as  pre- 
sented by  him  exhibits  an  association  of  the  characteristic  Ste.  Genevieve 
species,  Platycrinus  penicillus,  with  the  Amplexus  geniculates  and  its  asso- 
ciates. This  supposed  association  is  one  of  the  strongest  evidences  Ulrich 
has  presented  for  his  union  of  the  "Upper  Ohara"  with  the  Ste.  Genevieve, 
and  consequently  his  inclusion  of  the  Ste.  Genevieve  in  the  Chester  group. 
The  published  list  of  this  fauna,  however,  as  presented  by  Ulrich,  is  grossly 
misleading  as  to  facts.  He  has  not  separated  his  faunal  lists  in  accordance 
with  the  localities  from  which  they  were  collected,  but  has  lumped  together 
in  one  composite  list  all  those  forms  from  all  of  the  collections  which  he  has 
either  correctly  or  incorrectly  considered  as  representing  this  horizon.  The 
one  locality  that  has  always  been  mentioned  by  Ulrich  in  the  discussion  of 
this  question,  where  he  claims  to  have  collected  Platycrinus  penicillus  and 
other  unquestioned  Ste.  Genevieve  species  in  the  "Upper  Ohara,"  is  near 
Levias  in  Crittenden  County,  Kentucky,  where  the  fossils  are  said  to  have 
been  secured  less  than  fifty  feet  beneath  the  sandstone  formerly  called  Cypress 
by  him,  but  now  renamed  Bethel  by  Butts.  A  visit  to  this  locality  in  the 
summer  of  1918  by  the  writer  in  company  with  Mr.  Chas.  Butts,  established 
the  fact  that  the  Eosiclare  sandstone  had  been  mistakenly  identified  and 
mapped  as  Cypress  by  Ulrich,  and  that  consequently  these   Ste.   Genevieve 

xKy.  Geol.  Surv.,  Miss.  Ser.  in  W.  Ky.,  pp.   139-141,    (1918). 


142 


GEOLOGY  OF  HAEDIN  COUNTY 


limestone  species  were  actually  collected  from  the  Fredonia  limestone  instead 
of  from  the  "Upper  Ohara."  A  most  diligent  search  by  the  writer,  at  every 
favorable  locality  encountered  during  five  years  of  field  work,  has  failed  to 
disclose  a  single  instance  of  the  occurrence  of  the  index  fossils  of  the  Fredonia 
and  "Lower  Ohara"  passing  over  into  the  Shetlerville  or  any  part  of  the 
"Upper  Ohara/'  the  higher  faunas  being  characteristically  Chester  in  their 
relationships.  This  circumstance,  in  association  with  the  fact  that  the  Shet- 
lerville lies  unconformably  upon  the  "Lower  Ohara"  wherever  this  contact 
can  be  clearly  seen,  has  led  to  the  drawing  of  the  basal  line  of  the  Chester  in 
Hardin  County,  at  this  horizon. 

OOBEELATION 

A  full  discussion  of  the  correlation  of  the  Shetlerville  formation  will  be 
deferred,  and  the  problem  will  be  considered  along  with  the  correlation  of  the 
Eenault.  The  two  formations  are  very  closely  related  faunally.  Only  four 
species  are  restricted  to  the  Shetlerville,  these  being  Amphxus  genicuWus, 
Globo'crmus  unionmsis,  Talarocrinus  buttsi,  and  Spiriferina  subspinosa. 
Every  other  Shetlerville  species  except  two  forms  of  Pentremites  is  present 
also  in  the  Eenault  or  in  one  of  the  still  younger  Chester  formations,  and 
none  of  these  four  species  is  known  in  the  Ste.  Genevieve.  The  faunal  con- 
nection with  the  Ste.  Genevieve  is  much  less  close  than  with  the  Eenault, 
although  16  species  are  common  to  the  two  horizons.  Many  of  these,  however, 
are  long-range  forms  and  are  either  present  or  are  represented  by  closely 
allied  species  in  formations  still  older  than  the  Ste.  Genevieve,  and  the 
characteristic  index  fossils  of  the  Ste.  Genevieve,  Platycrinus  penicillus  and 
Pugnoides  ottumwa  have  nowhere  been  observed  in  the  Shetlerville  or  Eenault, 
As  will  be  shown  in  the  later  discussion  two  alternatives  are  possible  in  th( 
correlation  of  the  Shetlerville.  From  one  point  of  view  it  may  be  considered 
as  the  time  equivalent  of  the  Aux  Vases  sandstone,  while  in  another  way  it 
may  be  looked  upon  as  the  time  equivalent  of  the  sub-Eenault  unconformity 
of  Eandolph  County,  representing  essentially  the  time  interval  between  the 
end  of  the  deposition  of  the  Aux  Vases  sandstone  and  the  beginning  of  the 
Monroe  County  Eenault. 


Eenault  Foemation 

name  and  genebal  disteibution 

The  Eenault  formation  is  typically  developed  in  Monroe  County,  Illinois, 
and  was  named  from  Eenault  Township  of  that  county.  The  formation 
extends  northward  into  St.  Clair  County  for  a  short  distance,  southward  into 
Eandolph,  and  continues  across  Mississippi  Eiver  into  Ste.  Genevieve  County, 
Missouri.    Beyond  this  area  of  outcrop,  to  the  east  and  northeast,  the  Eenault 


UPPER   MISSISSIPPI^   SERIES,    CHESTER   GROUP  143 


formation  is  completely  buried  beneath  strata  of  younger  Chester  and  Penn- 
sylvanian  age.  The  formation  is  penetrated  in  the  oil  wells  of  eastern  Illinois, 
and  from  these  beds  some  of  the  oil  has  been  derived.  Composed  as  the 
formation  is,  of  limestones,  sandstones,  and  shales,  all  of  exceedingly  variable 
character,  the  heterogeneous  nature  of  the  constituent  beds  of  the  formation 
in  western  Illinois,  and  again  in  the  oil  fields  of  the  eastern  part  of  the  state, 
is  evidence  of  the  near-shore  origin  of  the  Eenault  sediments  in  these  areas.. 
The  position  of  the  shore-line  indicated  by  these  occurrences  must  have  been 
very  different  from- that  of  the  earlier  Ste.  Genevieve  sea  which  reached  far 
to  the  north  and  northwest,  at  least  as  far  as  Fort  Dodge,  Iowa. 

Hardin  County  lies  within  the  area  of  the  embayment  whose  shores  are 
indicated  by  the  Eenault  outcrops  in  western  Illinois  and  the  occurrence  of 
the  same  formation  in  the  oil  wells  of  the  eastern  part  of  the  state,  but  it  is 
a  long  distance  from  the  shore  line  indicated  and  consequently  the  character 
of  the  Eenault  sediments  in  Hardin  County  is  very  different  from  that  of 
those  which  accumulated  in  proximity  to  the  ancient  shore  line. 

The  outcrops  of  the  Eenault  formation  in  Hardin  County  are  much 
scattered,  and  they  nowhere  occupy  such  broad  areas  as  do  the  St.  Louis  and 
Fredonia  limestones.  One  reason  for  the  more  limited  extent  of  the  areas 
underlain  by  the  Eenault  than  by  the  older  limestones,  is  its  lesser  thickness ; 
but  its  position  immediately  beneath  a  thick,  massive,  bluff-forming  sand- 
stone, in  view  of  its  own  somewhat  shaly  character,  is  largely  responsible  for 
its  occurrence  in  narrow  belts  along  the  lower  slopes  of  hill  sides  whose  upper 
portions  rise  as  more  or  less  precipitous  bluffs  of  sandstone.  In  the  less 
faulted  portions  of  the  county,  such  narrow,  elongate  outcrops  of  the  forma- 
tion have  considerable  extent  longitudinally,  but  within  the  central,  faulted 
portion  of  the  county  even  these  narrow,  band-like  outcrops  commonly  do 
not  continue  for  any  great  distance  before  being  cut  off  by  faulting. 

In  the  southeastern,  unf  aulted  portion  of  the  county,  the  Eenault  occupies 
a  narrow  belt,  beneath  the  sandstone  bluff,  beginning  at  a  point  in  the  Ohio 
Eiver  bluff  a  little  over  three  miles  east  of  Cave  in  Eock,  extending  west- 
ward for  about  one  mile  and  then  in  a  northwesterly  direction  along  the  line 
of  bluffs  for  a  distance  of  five  miles  or  more  to  where  it  is  cut  off  by  the 
northeast-southwest  Peters  Creek  faults  which  determine  the  southeastern 
boundary  of  the  central  faulted  zone  of  the  county.  From  this  point  the 
formation  occurs  in  more  or  less  disconnected  outcrops  in  belt  number  three 
of  the  central  faulted  zone  (see  figure  3),  along  the  line  of  bluffs  running 
in  a  southwesterly  direction  parallel  with  the  major  lines  of  faulting,  to  a 
point  a  little  northwest  of  Elizabethtown.  Other  outcrops,  perhaps  among 
the  best  in  the  whole  county,  are  exposed  in  the  isolated  hill  with  two  sum- 
mits, which  lies  along  the  Ohio  Eiver  bank  just  southwest  of  Eosiclare.  One 
other  group  of  outcrops  occurs  a  little  less  than  a  mile  west  of  Peters  Creek 


144  GEOLOGY    OF   HARDIN   COUNTY 

Store,  in  a  narrow,  elongate,  downdropped  fault  block  which  is  an  off-shoot 
from  the  main,  much  larger,  downdropped  block  to  the  northwest. 

Within  the  median  belt,  number  two,  of  the  central  faulted  zone  (see 
figure  3),  the  Eenault  outcrops  are  much  scattered.  A  number  of  small  areas 
occur  in  the  very  complexly  faulted  region  northeast  and  southwest  of  Stone 
Church.  A  somewhat  larger  area  occurs  in  the  wedge-shaped  termination  of 
one  of  the  fault  blocks  south  of  Illinois  Furnace,  and  another  similar  area 
is  present  in  a  downdropped  block  southwest  of  St.  Josephs  School  and  east 
of  Wallace  Branch.  The  actual  limestone  outcrops  in  each  of  these  two  latter 
situations  are  heavily  talus-covered,  and  the  presence  of  the  formation  is 
indicated  chiefly  by  residual  fragments  of  the  formation  in  the  surficial 
covering. 

In  belt  number  one  of  the  faulted  zone,  the  most  extended  area  where 
the  Eenault  constitutes  the  surface  rock,  is  in  the  extreme  southwestern  part 
of  the  county  including  the  summit  of  Rich  Hill,  surrounding  Melcher  Hills, 
and  extending  northwest  and  southwest  to  the  Shetlerville  fault.  In  the  more 
northern  part  of  the  belt  the  Eenault  occupies  a  very  sinnous  strip  extending 
west  from  Gross  to  the  Hogthief  Creek  fault  west  of  Eock  Creek  School. 

From  the  Pope-Hardin  county  boundary  just  north  of  the  junction  of 
the  two  forks  of  Hicks  Branch  in  the  northwestern  portion  of  the  county,  the 
Eenault  occupies  its  normal  position  among  the  formations  that  partly 
encircle  the  Hicks  dome.  From  the  county  line  it  extends  in  a  northeasterly 
and  easterly  direction  to  the  Lee  fault,  where  the  outcrop  is  offset  over  a  mile 
to  the  southwest,  and  thence  continues  its  easterly  course  to  the  Wolrab  Mill 
fault.  An  excellent  outcrop  of  the  formation  occurs  in  the  hill  a  little  over 
one-half  mile  southwest  of  Eichorn. 

LITHOLOGIC    CHARACTER 

Unlike  the  Eenault  of  the  western  counties  of  Illinois,  where  the  forma- 
tion includes  limestones,  shales,  and  sandstones  of  various  sorts,  in  Hardin 
County  and  adjacent  parts  of  Illinois  and  Kentucky,  the  formation  is  made 
up  mostly  of  limestone  with  a  subordinate  amount  of  calcareous  shales  in 
the  form  of  partings  between  limestone  layers.  The  limestones  are  commonly 
of  gray  or  blue-gray  color,  and  of  crystalline  or  more  or  less  compact  texture ; 
some  beds  are  conspicuously  crinoidal,  some  beds  are  notably  cross-bedded, 
and  locally  there  are  oolitic  beds,  the  oolite  grains  being  commonly  much 
smaller  than  those  of  the  Ste.  Genevieve.  In  the  higher  beds  are  cherty  layers, 
which  upon  weathering  give  origin  to  very  characteristic  chert  fragments  of 
a  pale  color,  which  occur  in  the  residual  materials  as  small,  subcubical  or 
blocky  fragments.  On  the  whole  the  limestones  exhibit  a  considerable  range 
of  variation.  The  formation  as  a  whole  is  distinctly  more  calcareous,  with 
thicker  and  more  massive  beds  of  limestone  than  the  underlying  Shetlerville 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  145 

formation.  In  every  locality  where  exposures  of  the  Eenault  have  been 
observed,  the  surface  is  so  heavily  covered  with  talus  from  the  overlying 
massive  sandstone  formation  that  it  has  been  impossible  to  make  detailed  sec- 
tions of  the  formation,  the  outcrops  being  so  very  patchy  and  discontinuous 
that  the  most  that  is  seen  is  the  rather  massive  limestone  beds. 

THICKNESS 

In  the  measured  section  at  Fairview  bluff,  described  in  the  previous 
chapter  under  the  heading  "Ste.  Genevieve  formation,"  beds  14  to  18  inclusive, 
which  represent  the  Shetlerville  and  Eenault,  comprise  a  thickness  of  106 
feet.  The  upper  part  of  this  interval  is  talus-covered  in  the  south  bluff,  where 
the  section  was  for  the  most  part  taken,  so  that  the  base  of  the  superjacent 
sandstone  may  and  probably  does  continue  below  the  limits  indicated,  in  which 
case  the  thickness  of  the  two  formations  named  will  be  less  by  that  amount. 
They  doubtless  are  less  than  100  feet,  but  cannot  well  be  less  than  80  or  90' 
feet.  In  most  sections  where  these  two  formations  occur,  the  outcrops  are 
more  or  less  obscured  by  talus  deposits,  but  the  interval  in  which  they  must 
be  included  is  commonly  somewhat  less  than  100  feet,  and  perhaps  75  feet 
may  be  taken  as  a  fair  average.  The  thickness  of  the  Shetlerville  formation, 
characterized  by  the  Amplexus  geniculatus  fauna,  is  less  than  half  the  total 
thickness  of  the  interval,  and  probably  is  generally  about  25  feet,  which 
would  leave  the  thickness  of  the  Eenault  commonly  about  50  feet,  although 
in  places  the  thickness  may  be  somewhat  greater  or  considerably  less  than 
this. 

STRATIGRAPHIC  RELATIONS 

The  stratigraphic  relations  of  the  Eenault  with  the  subjacent  Shetlerville 
have  already  been  mentioned  in  connection  with  the  description  of  the  older 
formation.  At  one  locality  below  Eosiclare,  where  the  section  across  the  con- 
tact between  the  two  formations  has  been  observed,  apparently  there  is 
exhibited  a  distinct  line  of  unconformity  (see  figure  10).  This  phenomenon 
may  be  a  local  feature,  however,  with  no  especial  stratigraphic  significance. 

The  best  exhibition  in  Hardin  County  of  the  stratigraphic  relations  of 
the  Eenault  with  the  overlying  sandstone,  may  be  seen  in  the  Ohio  Eiver 
bluffs  east  of  Cave  in  Eock.  In  this  locality  the  actual  contact  of  the  sand- 
stone upon  the  limestone  is  exposed  in  the  bluff  near  the  line  between  sees.  16 
and  17,  T.  12  S.,  E.  10  E>.  (see  figures  11  and  12).  In  a  shallow  ravine 
one-fourth  mile  farther  west,  not  more  than  six  or  eight  feet  of  this  portion 
of  the  section  is  covered.  The  exposures  are  such  as  to  indicate  that  the 
sandstone  succeeds  the  limestone  abruptly,  with  no  intergradation  of  sedi- 
ments.    There  can  be  no  doubt  of  the  existence  of  an  unconformable  surface 

—10  G 


146 


GEOLOGY  OF  HAKDIN  COUNTY 


between  the  two  formations,  indicating  a  withdrawal  and  succeeding  readvance 
of  the  sea  in  the  Hardin  County  area  at  this  time.  At  the  first  locality 
described  above,  six  to  eighteen  inches  of  fragmental  material  is  present 
between  the  limestone  and  the  overlying  sandstone.  This  layer  is  composed 
of  flat  pebbles,  slabs  more  or  less  irregularly  disposed,  much  lime-sand,  quartz 
sand  of  large  rounded  grains,  and  many  fragments  of  fossils,  some  of  which 
are  worn  and  rounded.  The  layer  is  plainly  a  beach  formation  which  has  been 
accumulated  by  the  waves  and  currents.  The  exposure  is  shown  in  figures 
11  and  12. 


Fig.  11. — Photograph  of  the  unconformable  contact  of  the  Renault  limestone 
and  the  overlying  Bethel  sandstone,  in  the  bluff  3  miles  east  of  Cave  in  Rock,  on 
the  line  between  sees.  16  and  17,  T.  12  S.,  R.  10  B. 


West  of  Hardin  County,  in  the  Cache  River  bluffs  about  five  and  one-half 
miles  south  of  Vienna,  Johnson  County,  there  are  other  exposures  exhibiting 
unconformity  at  this  same  horizon.  In  this  section,  which  is  exposed  in  the 
railroad  cut  on  the  Chicago,  Burlington  and  Quincy  Railway,  the  Renault 
limestone  is  followed  by  a  sandstone  formation  12  feet  thick,  in  the  base  of 
which  there  is  a  calcareous  conglomerate  bed,  while  two  miles  to  the  east 
there  is  no  sandstone  present,  and  the  Paint  Creek  shales  with  thin  limestone 
layers,  rest  upon  the  Renault  with  a  conglomerate  bed  in  the  base  of  the 
upper  formation. 


UPPER    MISS1SSIPPIAX    SERIES,    CHESTER    GROUP 


147 


PALEONTOLOGY 

Although  some  of  the  beds  of  limestone  in  the  Renault  formation  are 
composed  largely  of  more  or  less  complete  shells  and  other  fossil  forms,  they 
are  commonly  so  firmly  imbedded  in  the  matrix  that  it  is  difficult  to  secure 
specimens  in  good  condition  for  accurate  identification.  Upon  some  of  the 
weathered  surfaces  good  fossils  can  be  collected.  Some  of  the  denser  and 
more  compact  beds  have  not  afforded  fossils  at  all,  and  but  few  localities  have 
been  met  with  where  the  more  shaly  layers  are  exposed  in  such  a  manner  as 
to  afford  good  collecting.  Under  these  circumstances  the  Renault  fauna  from 
Hardin   County  is  much  more  meagre  than   is  the   Shetlerville  fauna,  but 


Fig.    12. — Photograph    of    the    unconformable  contact  of  the  Bethel  sandstone  and 
the  Renault  limestone,  east  of  Cave   in  Rock.     Same  location  as  figure  11. 


sufficient  material  has   been   secured  from  a   number  of  localities  to  make 
clear  its  general  character. 

The  two  best  collections  from  the  Renault  limestone  of  Hardin  County 
have  been  secured  from  the  outcrops  in  the  Ohio  bluffs  above  the  railroad 
incline  of  the  Fairview  mine,  below  Rosiclare,  from  the  same  section  that  has 
furnished  one  of  the  best  collections  from  the  Shetlerville  formation;  and 
from  the  limestone  outcrop  at  the  mouth  of  the  Good  Hope  shaft  of  the  Fair- 
view  mine,  on  the  east  side  of  the  vein.  A  combined  list  from  these  two 
localities  is  given  below,  with  the  occurrence  of  the  species  indicated  in  the 
two  columns  at  the  right,  the  first  column  being  the  first  locality  mentioned, 
and  the  second  the  last  locality: 


148 


GEOLOGY  OF  HARDIN  COUNTY 


Fossils  from  the  Renault  formation  collected  in  the  Fairvieiv   bluff  and  at  the 

Good  Hope  shaft 


FOSSILS 


Triplophyllum  spinulosum  (M.-E.  and  H.) 

Talarocrinus  trijugis  M.  and  G 

Pentremites  godoni  DeFrance 

Pentremites  princetonensis  Ulrich 

Pentremites  pinguis  Ulrich 

Pentremites  arctibrachiatus  Ulrich 

Pentremites  buttsi  Ulrich 

Mesoblastus  glaber  (M.  and  W.) 

Meekopora  eximia  Ulrich 

Batostomella  sp 

Stenopora  sp 

Fenestella  cestriensis  Ulrich 

Fenestella  serratula  Ulrich 

Fenestella  teriax  Ulrich 

Polypora  cestriensis  Ulrich 

Lyrcpora  sp 

Septcpora  subquadrans  Ulrich 

Streblotrypa  nicklesi  Ulrich 

Cystcdictya  labiosa  Ulrich 

Phractopora  sp 

Orthotetes  kaskaskiensis  (McChesney) 

Productus  inflatus  McChesney 

Diaphragmus  elegans  (N.  and  P.) 

Pustula  sp 

Spiriferina  transversa  (McChesney) 

Spiriferina  spinosa  (N.  and  P.) 

Spirifer  increbescens  var.  transversa  Hall .  . 

Spirifer  leidyi  N.  and  P 

Reticulata  setigera  (Hall) 

Cliothyridina  sublamellosa  (Hall) 

Composita  trinuclea  (Hall) 

Orthcmychia  sp 

Phillipsia  sp 


In  1903  a  collection  was  made  by  H.  F.  Bain  from  the  outcrop  at  the 
mouth  of  the  Good  Hope  shaft  of  the  Fairview  mine,  the  same  locality  from 
which  the  collection  listed  in  column  2  of  the  preceding  table  was  obtained. 
The  following  species  were  identified  and  referred  to  the  Tribune  limestone 
by  Ulrich1,  some  of  which  have  not  been  recognized  in  the  more  recent  col- 


lections : 


iBull.   U.    S.   Geol.   Surv.,   No.   255,   p.   24,    (1905). 


UPPER   MISSISSIPPIAN"   SERIES,    CHESTER   GROUP  149 

Zaphrentis    spinulifera  Zeacrinus  maniformis 

Pentremites  godoni  Lyropora  ranosculum 

Pentremites  pyriformis  Lyropora  subquadrata 

Pentremites   cervinus  Spirifer  increbescens 

Stenopora  tuberculata  Spirifer  leidyi 

In  reproducing  this  list  here  a  number  of  manifest  typographical  errors 
have  been  eliminated.  On  translating  the  names  as  recorded  by  Ulrich  into 
the  generic  and  specific  terms  of  the  combined  list  given  above,  there  are  four 
entries  which  are  not  included  in  the  larger  list,  these  being  Pentremites 
cervinus,  Zeacrinus  maniformis,  Lyropora  ranosculum,  and  Lyropora-  sub- 
quadrata. There  is  perhaps  some  question  concerning  the  correct  identifica- 
tion of  Pentremites  cervinus  which  is  a  species  known  in  recent  collections 
only  in  much  younger  Chester  formations.  Zeacrinus  maniformis  is  really  a 
species  of  the  genus  Eupackycrinus  and,  from  its  known  occurrence  elsewhere, 
this  or  some  closely  allied  form  might  well  be  expected  in  the  fauna.  The 
most  important  additions  to  the  list  are  the  two  species  of  Lyropora.  The 
genus  has  been  recorded  in  collections  from  the  river  bluffs  above  the  Fair- 
view  incline,  but  it  is  represented  by  imperfect  bases  only,  while  the  examples 
submitted  by  Bain  evidently  were  so  preserved  that  the  species  themselves  were 
determinable. 

Full  collections  have  not  been  made  in  Hardin  County  from  other  Eenault 
localities  than  those  already  recorded,  but  a  few  forms  have  been  collected  at 
a  number  of  places.  A  good  exposure  of  the  formation  just  outside  of  Hardin 
County,  is  exhibited  in  the  bank  of  Ohio  River  a  short  distance  above  the 
mouth  of  Grand  Pierre  Creek,  where  some  of  the  weathered  surfaces  of  the 
limestone  are  covered  with  great  numbers  of  Pentremites.  A  number  of  well 
preserved  bases  of  the  bryozoan  genus  Lyropora  have  also  been  collected  at  this 
locality,  as  well  as  good  examples  of  Talarocrinus  trijugis  of  the  characteristic 
Eenault  type. 

In  all  these  faunas  from  the  Eenault  limestone  of  Hardin  County  and 
adjacent  regions,  the  most  characteristic  member  is  a  form  of  Talarocrinus, 
although  the  crinoid  is  not  commonly  abundant,  nor  is  it  often  found  in  a 
well-preserved  condition.  The  genus  Talarocrinus  was  present  in  the  Shet- 
lerville  formation,  but  the  species  commonly  met  with  there  is  T.  buitsi,  a 
form  with  a  small,  smooth,  subcorneal  base.  As  in  all  members  of  this  genus 
the  base  is  composed  of  two  plates,  but  instead  of  forming  a  subcorneal  or 
narrowly  bowl-shaped  cup  as  in  T.  buttsi,  the  base  in  the  Eenault  form  is 
disk-shaped  with  the  suture  between  the  two  plates  rather  deeply  impressed, 
giving  to  it  a  distinctly  bilobed  appearance.  This  type  of  base  may  be  present 
in  a  number  of  different  species  of  Talarocrinus  which  may  either  be  associated 
or  be  characteristic  of  somewhat  different  geological  horizons,  or  they  may  be 
in  part  geographic  variations  of  one  type.  In  probably  99  cases  out  of  100 
it  is  onlv  the  bilobed  base  of  the  crinoid  or  detached  radial  plates  that  are 


150  GEOLOGY    OP   HARDIN    COUNTY 

observed  in  the  fossil  condition,  so  that  if  they  do  represent  a  number  of 
species  the  distinguishing  specific  characters  can  rarely  be  determined.  This 
type  of  Talarocrinus  has  been  observed  in  the  Shetlerville  formation  in  only 
one  locality,  and  there  it  is  represented  by  a  single  specimen  where  it  was 
collected  loose  from  a  glade-like  surface,  and  it  is  quite  possible  that  this  one 
example  may  have  originated  in  a  layer  of  the  Eenault  limestone  a  little 
higher  up.  In  any  event  there  is  a  distinct  faunal  zone  in  the  Hardin  County 
section  which  is  characterized  by  the  species  of  Talarocrinus  with  a  bilobed 
base,  and  this  horizon  is  Eenault. 

Most  of  the  associates  of  the  bilobed  Talarocrinus  in  the  Eenault  lime- 
stone are  present  also  in  the  Shetlerville  formation  below,  but  there  is  a 
greater  variety  of  Pentremites,  and  among  them  are  introduced  for  the  first 
time  those  forms  of  the  "piriformis"  type  with  the  elongate  base.  The  pecu- 
liar type  of  Talarocrinus,  the  elongate  Pentremites,  and  the  common  presence 
of  numbers  of  Lyropora  bases  constitute  the  characteristic  features  of  the 
Eenault  fauna.  Every  species  in  the  fauna  occurs  elsewhere  in  the  Lower 
Chester  formations,  especially  in  Eandolph  and  Monroe  counties,  Illinois,  and 
none  of  the  characteristic  Ste.  Genevieve  limestone  species  have  been  found 
in  the  formation.  The  entire  fauna  is  distinctly  Chester  in  all  of  its  features, 
but  it  is  a  Chester  fauna  in  which  the  genus  Archimedes  is  almost  wanting. 
The  spiral  axes  of  this  genus  are  rarely  met  with  in  the  Eenault  and  where 
they  are  present  the}^  are  not  common;  in  the  two  best  collections  made  in 
Hardin  County  the  genus  has  not  been  met  with  at  all,  and  only  one  or  two 
examples  have  anywhere  been  seen  by  the  writer  in  the  Eenault  of  the  county. 

CORRELATION 

The  correlation  of  the  Shetlerville  and  Eenault  formatious,  the  "Upper 
Ohara"  limestone  of  Ulrich,  is  a  question  which  constitutes  the  most  funda- 
mental difference  between  Ulrich  and  the  writer  in  the  interpretation  of  the 
Chester  group,  and  in  considering  this  question  a  somewhat  critical  examina- 
tion into  the  methods  of  correlation  advocated  and  used  by  Ulrich  must  be 
made.  Ulrich  has  had  much  to  say  in  regard  to  the  unsatisfactory  results 
to  be  attained  in  correlation  by  the  method  of  "matching"  genera  and  species. 
In  regard  to  this  method  he  says  in  one  place1,  "Under  certain  conditions,  and 
in  so  far  as  basal  stratigraphic  conceptions  are  concerned,  the  idea  is  correct 
enough ;  but  when  it  comes  to  the  accurate  identification  of  minor  units  of  the 
time  scale  it  is  inadequate  and  indeed  more  likely  to  lead  us  astray  than  to 
the  truth."  It  must  be  admitted  that  the  method  of  correlation  by  matching 
genera  and  species  has  been  abused  by  reason  of  the  too  loose  practices  in  the 
discrimination  of  fossil  species,  but  to  replace  it  by  a  method  of  matching 
individuals  would  be  equally  objectionable.     In  regard  to  this  new  method 

1Bull.  Geol.   Soc.  Amer.,  vol.   27,  p.   472,    (1916). 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  151 

Ulricli  says1 :  "The  new  criterion  is  based  on  the  logical  belief  that  combina- 
tions of  biologically  unimportant  characters  can  have  existed  but  once,  and 
that  they  endured  for  only  short  periods  of  time.  Accordingly,  absolute 
identification  of  such  minor  modifications  of  species  in  widely  separated 
localities  is  regarded  as  establishing  the  essential  contemporaneity  of  these 
occurrences."  In  the  application  of  this  method  its  author  concludes  that  if 
he  can  secure  two  individuals  of  a  given  species  that  are  exactly  alike  as 
regards  a  number  of  arbitrarily  selected  minor  characteristics,  the  two  speci- 
mens must  be  contemporaneous.  It  is  a  well  recognized  fact  that  all  species 
are  variable,  some  more  so  and  others  less.  It  is  also  an  established  fact  that 
each  species  has  lived  during  a  time  period  of  greater  or  less  duration,  some 
species  being  much  longer  lived  than  others,  and  as  our  observations  are 
extended  we  are  constantly  accumulating  new  data  in  regard  to  the  duration 
in  geologic  time  of  fossil  species.  Now  the  liability  of  finding  two  examples 
of  a  given  species  that  are  identically  alike  in  a  number  of  characters,  is 
clearly  dependent  upon  the  number  of  examples  which  may  come  under 
observation.  If  the  observer  compares  a  dozen  specimens,  all  from  the  same 
bed  at  one  locality,  or  from  different  beds  at  different  localities,  no  two  may 
be  exactly  alike,  but  if  a  thousand  individuals  be  examined  two  or  more  that 
are  essentially  alike  in  all  the  characters  selected  for  comparison  are  more 
likely  to  be  met  with.  From  the  very  nature  of  the  case  the  longer-lived  a 
particular  specific  form  may  be,  other  factors  being  equal,  the  greater  number 
of  individuals  will  be  available  for  comparison,  and  consequently  the  greater 
liklihood  will  there  be  that  exactly  similar  individuals  will  be  found;  under 
these  circumstances  it  is  apparent  that  there  is  no  basis  for  a  "logical  belief ' 
that  such  similar  individuals  must  have  been  contemporaneous. 

In  his  Chester  correlations  Ulrich  has  laid  great  stress  upon  the  im- 
portance of  the  members  of  the  genus  Pentremites,  and  in  his  Kentucky  paper 
he  has  named  without  descriptions,   at  least   23  new  species  and  varities.2 

iBull.   Geol.    Soc.   Amer.,   vol.    27,   p.    456,    (1916). 

2  This  practice  of  naming  species  without  adequate  descriptions  cannot  be  too  severely- 
criticised.  Some  of  the  forms  may  be  recognized  with  a  fair  degree  of  certainty  from 
the  illustrations,  but  in  some  cases  there  are  as  great  differences  shown  among  the 
examples  figured  to  represent  a  single  species  as  are  shown  between  examples  that  are 
referred  to  different  species.  If  strict  justice  were  done  none  of  the  species  would  deserve 
recognition.  The  sorts  of  characters  which  seem  to  have  been  used  by  Ulrich  for  the 
differentiation  of  his  several  species  are  the  flatness  or  degree  of  concavity  of  the  inter- 
ambulacral  spaces,  the  straightness  or  concavity  of  the  base  from  the  lower  ends  of  the 
ambulacra  to  the  stem  attachment,  and  the  pedunculation  of  the  base.  Such  characters 
as  the  flatness  or  concavity  of  the  interambulacral  areas,  which  may  actually  vary  in 
the  several  areas  of  one  individual,  are  considered  by  him  as  having  real  phylogenetic 
value.  Other  characters  which  have  been  used  in  his  differentiation  of  species  are  to  be 
found  in  the  ambulacral  areas,  and  these  are  of  somewhat  higher  taxonomic  value  than 
the  mere  variations  in  actual  form.  Many  internal  characters  of  the  Pentremites,  con- 
nected with  the  hydrospires,  are  disregarded  altogether,  although  they  might  be  expected 
to  exhibit  features  of  much  greater  phylogenetic  value  than  any  of  those  used,  but  such 
characters  require  laborious  preparation  and  are  difficult  to  observe,  and  even  under 
the  best  of  circumstances  they  would  be  well  exhibited  in  only  occasional  individuals. 
However,  any  classification  or  grouping  of  the  members  of  this  genus  based  upon  any- 
thing less  than  all  the  characters,  both  external  and  internal,  must  be  considered  as 
artificial.  It  is  undoubtedly  safe  to  state  that,  with  the  data  Ulrich  has  supplied,  no 
one  would  be  able  to  successfully  distribute  the  pyriform  examples  of  Pentremites  in  a 
large  collection  among  his  species  Pentremites  pyriformis,  girtyi,  welleri,  lyoni,  buttsi, 
abruptus,  and  symmetricus. 


152  GEOLOGY    OF    HARDIN    COUNTY 

This  genus  is  certainly  an  important  one  in  the  Chester  faunas,  many  of  the 
forms  named  by  Ulrich  are  doubtless  good  species,  and  the  importance  of  the 
genus  for  the  purposes  of  correlation  cannot  be  denied,  but  by  using  the 
method  of  matching  individuals  among  the  species  of  this  genus,  the  correla- 
tion of  any  formation  from  the  St.  Louis  limestone  to  the  Paint  Creek  of 
the  Chester,  with  any  other  formation  in  the  same  series,  can  be  established. 
Ulrich  so  regards  his  determinations  of  the  Pentremites  that  the  correlation 
of  the  "Upper  Ohara"  limestone  with  the  Renault  seems  to  be  unreasonable. 
One  of  his  new  species  of  Pentremites  is  P.  princetonensis.  This  is  said  to  be 
the  "most  common  species  of  the  genus  in  the  Ste.  Genevieve  limestone/' 
and  the  specimens  which  he  illustrates  are  from  the  Fredonia  oolite  and  the 
"Upper  Ohara"  limestone.  This  occurrence  of  the  species  constitutes  one  of 
his  reasons  for  including  both  of  these  formations  in  the  same  stratigraphic 
unit,  the  Ste.  Genevieve  limestone.  In  his  original  manuscript  he  did  not 
recognize  this  species  at  all  in  the  Renault  of  Monroe  and  Randolph  counties, 
but  after  being  shown  an  individual  from  the  Renault  which  agreed  exactly 
in  all  its  details  with  the  type  of  the  species  from  the  "Upper  Ohara/'  and 
after  admitting  his  inability  to  distinguish  the  two  examples  although  both 
were  well-preserved  specimens,  he  added  the  following  statement  regarding 
the  species1,  "A  variety  distinguishable  only  when  the  specimens  preserve  the 
minute  characters  of  the  ambulacral  areas,  is  found  in  both  the  Renault  and 
Paint  Creek  formations  of  Illinois."  Of  the  two  common  types  of  Pentre- 
mites in  the  Renault  fauna  of  western  Illinois,  one  includes  individuals  which 
are  perfectly  typical  of  the  forms  named  P.  princetonensis  and  P.  pinguis  by 
Ulrich,  and  which  are  indistinguishable  from  examples  of  the  same  species 
from  the  Shetlerville  and  Renault  formations  of  Hardin  County  (see  plate 
IV,  figs.  1-12),  and  the  other  is  a  pyriform  type  which  furnishes  examples 
which  exactly  match  examples  of  P.  huttsi,  another  of  Ulrich's  newly  named 
species  from  the  "Upper  Ohara"  (see  plate  IV,  figs.  16-20).  By  unquali- 
fiedly using  the  method  of  matching  individuals,  the  Renault  of  Monroe 
County  can  be  shown  to  be  the  equivalent  of  the  Renault  or  Shetlerville  of 
Hardin  County,  or  even  of  the  Fredonia  member  of  the  Ste.  Genevieve  lime- 
stone. By  matching  individuals  of  P.  princetonensis  the  St.  Louis  limestone 
can  be  made  to  be  the  equivalent  of  the  Renault  of  either  Hardin  or  Monroe 
counties.  Furthermore,  by  matching  individuals  of  P.  godoni  (P.  planus 
Ulrich)  from  the  Paint  Creek  of  St.  Clair  County  and  from  the  Renault  of 
Hardin  County  (see  plate  IV,  figs.  33-36),  these  two  formations  can  be  shown 
to  be  contemporaneous.  Since  things  equal  to  the  same  thing  must  be  equal 
to  each  other,  it  might  be  demonstrated  by  all  of  these  matchings  that  the 
St.  Louis  limestone  is  the  correlate  of  the  Paint  Creek.     It  is  to  absurdities 


Form.   Chester  Ser.   in  W.   Ky.,  p.   243,    (1918). 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  153 

of  this  sort  that  we  are  bound  to  be  led  if  the  method  of  correlation  by  match- 
ing individuals  is  followed  systematically. 

Any  student  who  will  take  the  time  to  compare  large  numbers  of  Pen- 
tremites  from  different  horizons  and  from  different  localities  of  the  same 
horizon,  will  find  an  almost  endless  variety  of  individuals.  Practically  every 
collection  will  exhibit  some  varieties  not  found  elsewhere,  and  a  grouping  of 
individuals  which  seems  to  be  satisfactory  in  the  collection  from  one  locality 
is  likely  to  prove  to  be  unsatisfactory  in  a  collection  from  another  locality, 
perhaps  of  the  same  horizon.  These  forms  undoubtedly  exhibit  a  considerable 
degree  of  contemporaneous,  geographic  variation  as  well  as  variation  with  the 
progress  of  time,  and  for  such  geographic  variation  there  seems  to  be  no  place 
in  the  system  devised  by  Ulrich. 

Those  species  of  the  genus  Talarocriniis  with  the  thickened  plates  form- 
ing a  bilobecl  base,  have  been  considered  by  the  writer  as  very  characteristic 
of  the  Lower  Chester  faunas,  more  especially  of  the  Eenault,  and  the  com- 
mon presence  of  such  species  in  the  Eenault  of  Monroe  and  Randolph  counties 
and  in  the  "Upper  Ohara"  of  southeastern  Illinois,  has  been  considered  as 
one  of  the  lines  of  evidence  for  the  correlation  of  these  units.  Ulrich  does 
not  agree  with  this  conclusion  for  the  reason  that  in  his  method  of  matching 
individuals  he  has  not  as  yet  found  two  examples,  one  from  the  typical 
Eenault  and  the  other  from  the  "Upper  Ohara,^  which  he  considers  to  be 
exactly  alike  in  all  particulars.  In  considering  this  evidence,  however,  it 
must  be  constantly  kept  in  mind  that  complete  examples  of  Talarocriniis  are 
exceedingly  rare.  Many  separate  radials  and  plates  of  the  base,  and  an 
occasional  dorsal  cup,  are  met  with  at  most  localities,  but  probably  not  one 
example  in  a  thousand,  which  can  be  easily  recognized  as  being  a  member  of 
the  genus,  preserves  the  entire  body  of  the  crinoid,  which  must  be  available 
to  make  the  comparison  Ulrich  demands.  It  is  not  reasonable  to  insist  that 
because  exactly  similar  examples  have  not  been  found  among  the  score  of 
individuals  that  have  been  available  for  comparison,  that  such  similarities 
would  not  be  met  with  among  the  thousands  of  examples  that  are  represented 
by  fragments  only.  Furthermore,  the  fact  known  to  every  observing  pale- 
ontologist, that  the  characters  of  different  groups  of  organisms  possess  varying 
time  values,  has  a  direct  bearing  upon  the  problem  before  us.  Generic  char- 
acters in  some  groups  of  organisms  may  possess  as  limited  time  value  as 
specific  or  varietal  characters  in  other  groups.  Many  brachiopods,  for  in- 
stance, are  notoriously  conservative  and  slow  changing  and  are  consequently 
of  less  time  value  than  some  other  fossil  organisms,  and  in  such  forms  the 
matching  of  individuals  could  not  possibly  furnish  any  basis  for  correlation. 
The  genus  Talarocriniis,  on  the  other  hand,  is  one  of  the  camerate  crinoid s 
which  are  notoriously  rapidly  changing  forms,  and  furthermore  this  genus 
is  one  of  the  last  representatives   of  the  order  and   lived   at  a   time  when 


154  GEOLOGY    OF    HARDIN    COUNTY 

morphological  changes  were  taking  place  in  the  group  with  extreme  rapidity. 
It  is  well  known  that  organisms  in  this  stage  of  their  evolution  are  not  only 
changing  rapidly  as  a  whole,  but  are  subject  to  very  great  geographic  varia- 
tions, so  that  species  are  liable  to  possess  only  limited  geographic  range.  In 
a  group  of  organisms  of  this  sort  it  is  evident  that  the  generic  characters 
may  have  even  greater  correlative  value  than  the  specific  or  varietal  characters 
of  some  other  groups.  One  of  the  great  absurdities  of  the  method  of  correla- 
tion by  matching  individuals  is  the  fact  that  no  recognition  is  given  to  the 
possibility  of  contemporaneous  geographic  modifications  within  a  genus,  which 
may  be  of  specific  value. 

The  facts  in  regard  to  the  occurrence  of  members  of  the  genus  Talaro- 
crinus of  the  type  indicated,  are  as  follows.  In  Monroe  and  Eandolph  coun- 
ties examples  occur  in  the  Eenault  and  Paint  Creek  formations  and  nowhere 
else.  They  are  far  more  common  in  the  Eenault,  and  no  fairly  complete 
fauna  has  anywhere  been  collected  from  the  limestone  of  this  formation 
without  producing  some  examples,  although  complete  specimens  are  rare.. 
Many  Paint  Creek  collections  have  been  made  with  no  representative  of  the 
genus,  but  they  do  occur  rarely.  In  Hardin  County  and  the  adjacent  portions 
of  Illinois  and  Kentucky,  the  "Upper  Ohara"  is  the  Talarocrinus  horizon, 
and  examples  of  the  characteristic  bases  or  of  the  radial  plates  may  be  found 
in  most  localities  if  sufficient  search  is  made;  they  have  about  the  same 
relation  to  the  fauna  as  a  whole  as  in  the  Eenault  of  Monroe  and  Eandolph 
counties.  Complete  specimens  are  rare,  however,  and  no  examples  have  been 
observed  that  are  exactly  similar  to  specimens  from  the  Eenault  of  the  more 
western  counties,  although  individuals  sufficiently  alike  to  be  considered  as 
coming  within  the  limits  of  the  same  species  have  been  studied.  In  the  Paint 
Creek  horizon  of  Hardin  County  and  the  adjacent  region,  specimens  of 
Talarocrinus  have  been  met  with  but  rarely.  In  carrying  the  observations 
still  farther  south,  this  type  of  Talarocrinus  is  found  to  be  characteristic  of 
and  limited  to  the  Gasper  limestone  of  Butts  and  Ulrich.  In  his  list  of 
Gasper  fossils,  Ulrich1  records  four  species  of  the  genus,  three  of  which  are 
from  the  lower  Gasper  and  only  one  from  the  upper  member  of  that  forma- 
tion, a  distribution  which  compares  with  that  of  the  same  genus  in  the  Eenault 
and  Paint  Creek  of  western  Illinois.  Indeed,  Ulrich  cites  much  evidence 
for  the  correlation  of  the  Gasper  with  the  typical  Eenault  and  Paint  Creek. 
On  the  other  hand  Ulrich  does  not  recognize  the  presence  of  Talarocrinus 
in  any  list  of  Fredonia  species  nor  in  zone  1  of  the  Ohara,  which  is  the 
"Lower  Ohara"  of  this  report  and  which  is  truly  of  Ste.  Genevieve  age.  Now 
the  results  of  Ulricrr's  correlations  are  to  consider  the  Talarocrinus-he&vmg 
Gasper  horizons  of  Kentucky  east  of  Caldwell  County  as  equivalent  to  the 
Tatar ocrimis-be&rmg  Eenault  and  Paint  Creek  of  western  Illinois,  the  two 

>Form.   Chester  Ser.  in  W.  Ky.,  pp.   147-148,    (1918). 


UPPER    MISSISSIPPI^    SERIES,    CHESTER   GROUP  155 

regions  lying  at  opposite  sides  of  the  basin  involved.  In  the  intervening 
region,  however,  in  southeastern  Illinois,  the  Talarocrinus  beds  are  considered 
by  him  as  lying  entirely  beneath  the  Gasper  Talarocrinus  horizon  to  the  east 
and  the  Eenault  Talarocrinus  horizon  to  the  west,  notwithstanding  the  fact 
that  every  single  associate  of  this  type  of  Talarocrinus  in  the  region,  is  known 
also  from  the  typical  Eenault  or  from  some  still  younger  Chester  fauna,  and 
that  the  index  fossils  of  the  Ste.  Genevieve  are  unknown  in  the  fauna.  In 
this  place  attention  may  again  be  called  to  the  fact  that  Ulrich  himself 
formerly  recognized  the  "Upper  Ohara"  outcrop  at  the  mouth  of  the  Fairview 
mine  at  Rosiclare,  as  Tribune,  which  is  the  name  first  applied  to  the  Gasper1, 
a  correlation  which  he  must  necessarily  abandon  with  his  present  views. 

In  the  author's  opinion  every  bit  of  the  paleontologic  evidence  points 
to  the  correlation  of  the  "Upper  Ohara"  of  Hardin  County  with  the  Renault 
of  Monroe  and  Randolph  counties;  indeed,  the  correlation  may  be  considered 
as  being  so  well  established  that  there  need  be  no  hesitation  in  extending  the 
name  Renault  into  southeastern  Illinois,  as  is  done  in  this  report. 

In  spite  of  Ulricas  opinion  that  "the  occurrence  of  a  single  finely  drawn 
variety  in  two  or  more  widely  separated  places — be  they  in  the  same  province 
or  not — is  a  more  trustworthy  indication  of  the  contemporaneity  of  the  beds 
containing  it  than  would  be  any  quantity  of  the  indefinite  testimony  afforded 
by  generic  alliances,"  it  still  seems  to  the  writer  that  a  consideration  of  all 
the  evidence  afforded  by  a  fossil  fauna  is  more  likely  to  lead  to  its  correct 
interpretation.  Generic  alliances  have  their  values  in  correlation,  as  do 
specific  identities  and  individual  similarities,  but  for  obtaining  the  most 
reliable  results,  all  these  factors  must  be  considered,  and  the  whole  make-up 
and  complexion  of  the  fauna  must  be  scrutinized.  Such  an  examination  of 
the  "Upper  Ohara"  faunas  can  lead  to  but  one  conclusion,  that  being  that 
these  faunas  have  their  closest  relationships  with  the  Renault  faunas  of 
southwestern  Illinois. 

Ulrich2  has  said  "the  function  of  the  fossils  is  to  identify  horizons."  In 
another  place  he  says3  "A  single  species,  or  preferably  two  or  three  constantly 
associated,  rare  or  common  species,  may  be  of  greater  practical  utility  and 
often  of  more  exact  value  in  correlation  than  all  the  remainder  of  a  large 
fauna."  Another  principle  he  has  enunciated4  is  that  "The  sequence  of  minor 
but  well-defined  life  zones,  when  found  to  agree  in  widely  separated  localities, 
is  to  be  regarded  as  highly  significant  in  establishing  the  essential  contem- 
poraneity of  the  respective  zones." 

In  Hardin  County  and  the  adjacent  region,  the  fossils  do  serve  to  identify 
a  number  of  definite  horizons,  and  these  life  zones  do  have  a  definite  sequence 
throughout  the  region.     In  that  portion  of  the  geological  section  under  im- 

JU.   S.  Geol.   Surv.,   Bull.  No.   255,  p.   24,    (1905). 

2  Bull.  Geol.  Soc.  Amer.,  vol.   27,  p.  488,    (1916). 

3  Bull.   Geol.   Soc.  Amer.,  vol.    22,  p.   509,    (1911). 
4Loc.  cit.,  p.   510,    (1911). 


156  GEOLOGY  OF  HAUDIN  COUNTY 

mediate  consideration  there  is  a  well  defined  lower  zone  characterized  especially 
by  Platycrinus  penicillus  and  Pugnoides  ottumwa;  this  zone  is  followed  by 
one  in  which  the  above  mentioned  species  are  wanting  and  which  is  character- 
ized especially  by  Amplexus  geniculatus.  This  in  turn  is  succeeded  by  a 
zone  in  which  there  are  present  one  or  more  species  of  Talarocrinus  with 
thickened  basal  plates,  this  thickening  giving  to  the  base  a  distinctly  bilobed 
appearance.  Members  of  the  genus  Pentremites  are  common  throughout  all 
three  zones,  as  are  brachiopods  and  other  forms.  There  are  a  few  species 
which  occur  in  all  three  zones,  but  nearly  all  of  those  in  the  second  zone  are 
known  also  in  the  upper  one,  while  the  community  between  the  first  and 
second  zones  is  much  less  evident. 

The  succession  across  the  same  interval  in  the  Eandolph-Monroe  county 
region  is  as  follows :  first  a  Platycrinus  penicillus-Pugnoides  ottumwa  fauna, 
identical  in  all  essential  respects  with  the  same  fauna  in  Hardin  County, 
followed  by  the  Aux  Vases  sandstone  without  fossils  of  any  sort,  and  this 
succeeded  by  beds  which  are  characterized  by  species  of  Talarocrinus  having 
the  same  type  of  bilobed  base,  some  of  which  are  specifically  identical  with 
forms  present  in  the  third  zone  in  Hardin  County.  The  first  and  third  zones 
respectively,  in  the  two  regions,  are  considered  by  the  writer  to  be  equivalent, 
but  there  may  be  alternate  interpretations  of  the  middle  zone.  It  is  an  estab- 
lished fact  that  an  important  unconformity  exists  at  the  base  of  the  Eenault 
in  Eandolph  and  Monroe  counties,  which  makes  it  possible  that  the  beds  with 
Amplexus  geniculatus  in  Hardin  County  may  be  a  somewhat  older  member 
of  the  Eenault  which  was  not  deposited  in  the  more  western  portion  of  the 
basin.  Under  this  interpretation  the  Aux  Vases  sandstone  of  Eandolph 
County  would  be  represented  by  the  unconformity  between  the  Ste.  Genevieve 
limestone  and  the  Amplexus-heaimg  beds  in  Hardin  County,  and  the  Shetler- 
ville  would  be  represented  by  the  unconformity  at  the  base  of  the  Eenault  in 
Eandolph  County.  An  alternative  interpretation  would  be  to  consider  the 
Amplexus  geniculatus-bearmg  beds  of  the  Shetlerville  formation,  as  the  time 
equivalent  of  the  Aux  Vases  sandstone.  The  Illinois  basin  in  Chester  time  was 
an  embayment  lying  between  Ozarkia  on  the  west  and  Cincinnatia  on  the 
east,  extending  northward  to  near  the  center  of  Illinois.  The  present  loca- 
tion of  the  outcrops  of  the  Aux  Vases  sandstone  in  the  Mississippi  Eiver 
bluffs  of  Illinois  and  Missouri,  is  near  the  western  shore  line  of  the  Chester 
basin,  where  sand  deposits  would  naturally  be  accumulated.  The  Hardin 
County  section  lies  near  the  center  of  this  ancient  basin,  probably  fifty  or 
sixty  miles  from  the  nearest  shore.  It  was  beyond  the  zone  into  which  the 
beach  sands  of  the  time  were  conveyed,  and  although  the  sea  was  shallow  as 
is  shown  by  the  cross-bedding  of  the  strata,  the  only  sediments  being  deposited 
were  the  calcareous  remains  of  organisms  which  inhabited  the  basin,  and  the 
finely  divided  particles  of  mud  which  were  held  in  suspension  far  beyond 


UPPER    AIISSISSIPPIAX    SERIES,    CHESTER    GROUP 


157 


where  the  sand  was  dropped.  These  conditions  might  reasonably  account 
for  the  equivalency  of  the  Shetlerville  limestone  and  shale  of  Hardin  County, 
with  the  Aux  Vases  sandstone  of  the  Mississippi  Valley.  The  correlation  of 
the  geologic  sections  in  the  two  regions,  viz.,  Randolph  Count}7,  Illinois,  and 
Hardin  County,  Illinois,  as  interpreted  by  Ulrich  and  again  as  interpreted 
by  the  writer,  is  shown  in  the  two  accompanying  tables. 

In  the  following  table  are  included  all  those  forms  in  the  Renault  fauna 
of  Hardin  County  that  have  been  specifically  identified,  and  their  occurrence 
'in  other  regions  and  horizons  is  indicated  in  the  columns  to  the  right  and 
left.  In  the  columns  to  the  right  the  occurrence  of  the  species  in  equivalent 
or  younger  formations  is  indicated,  while  in  the  columns  to  the  left  the  occur- 
rence in  older  beds  is  shown.  When  the  species  are  represented  elsewhere  by 
closely  allied  forms,  not  specifically  the  same,  the  fact  is  indicated  by  0  in 
the  proper  column ;  specific  identity  is  indicated  by  X.  In  column  1  a  record 
is  made  of  the  occurrence  in  formations  of  pre-Ste.  Genevieve  age;  column  2 
is  Ste.  Genevieve,  and  column  3,  Shetlerville.  On  the  right,  column  4  is  the 
Renault  limestone  of  Monroe  and  Randolph  counties;  column  5  is  the  Paint 
Creek;  and  column  6,  any  Chester  formation  younger  than  the  Paint  Creek. 

Table  shoicing  geologic  range  of  the  Renault  fauna 


RENAULT  FAUNA 


0 


X 


X 


X 

? 

X 
X 

X 

X 
X 
X 
X 
X 

o 
o 

X 
X 
X 


Triplophyllum  spinulosum. 

Talarocrinus  trijugis 

Pentremites  godoni 

Pentremites  princetonensis 

Pentremites  pinguis 

Pentremites  buttsi 

Mesoblastus  glaber 

Meekopora  eximia 

Stenopora  tuberculata .... 

Fenestella  cestriensis 

Fenestella  serratula 

Fenestella  tenax 

Polypora  cestriensis 

Lyropora  ranosculum 

Lyropora  subquadrata .... 
Septopora  subquadrans .  .  . 

Streblotrypa  nicklesi 

Cystodictya  labiosa 

Phractopora  sp 

Orthotetes  kaskaskiensis .  .  . 
Productus  inflatus 


X 

X 

0 

X 

X 

X 

X 

X 

0 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

158 


GEOLOGY    OF    HAKDIN    COUNTY 
Table  showing  geologic  range  of  the  Renault  fauna — Concluded 


RENAULT  FAUNA 


0 

X 

0 

X 

X 

0 

X 

X 

X 

X 

X 

X 

X 

X 

X 

Diaphragmus  elegans 

Spirif  erina  spinosa 

Spirif  erina  transversa 

Spirifer  increbescens  var.  transversalis 

Spirif er  leidyi 

Reticularia  setigera 

Cliothyridina  sublamellosa 

Composita  trinuclea 


X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

The  known  Renault  fauna  of  Monroe  and  Randolph  counties.  Illinois,  is 
considerably  larger  than  that  of  Hardin  County,  but  the  above  tabulation 
shows  that  every  species  from  Hardin  County,  except  two,  is  present  also  in 
the  fauna  of  the  typical  Renault  of  the  more  western  counties.  These  two 
exceptional  species,  although  not  as  yet  recognized  in  the  Renault  of  the  west, 
are  both  known  from  Chester  formations  younger  than  the  Renault  in  the 
same  region.  Most  of  the  additional  species  in  the  faunas  of  the  typical 
Renault  are  crinoids  which  even  in  that  region  are  known  only  locally,  many 
of  the  collections  being  essentially  like  those  that  have  been  recorded  from 
Hardin  County.  In  addition  to  the  identity  of  species  in  the  Renault  faunas 
of  Hardin,  and  Monroe  and  Randolph  counties,  the  same  faunal  peculiarities 
are  exhibited  in  both  regions.  Both  faunas  are  characterized  by  species  of 
Tatar ocrinus  with  the  bilobed  base,  some  species  being  common  to  the  two 
regions;  in  both  faunas  the  bases  of  Lyropora  are  present  in  most  collections, 
and  in  some  localities  they  are  common;  it  is  not  always  possible  to  identify 
the  species  of  this  bryozoan  because  of  the  lack  of  preservation  of  the  fenes- 
trated portion  of  the  colony,  but  it  is  quite  certain  that  the  same  species  occur 
in  both  regions.  Furthermore  the  Renault  association  in  both  regions  is  a 
fauna  with  decided  Chester  aspect  in  which  the  genus  Archimedes  is  usually 
rare,  or  is  wholly  absent,  in  very  strong  contrast  with  the  higher  Chester 
faunas.  The  faunal  characteristics  of  these  two  limestones  in  the  two  regions 
of  Illinois  are  so  uniformly  the  same,  that  their  correlation  on  the  basis  of 
the  paleontologic  evidence  cannot  be  gainsaid. 

The  stratigraphic  succession  in  southeastern  and  in  western  Illinois 
affords  other  evidence  supporting  that  of  the  fossils  in  the  same  correlation. 
In  both  regions  the  Renault  is  followed  by  an  arenaceous  or  at  least  siliceous 
formation,  the  Yankeetown  of  Monroe  and  Randolph  counties,  and  the  Bethel 
sandstone  of  southeastern  Illinois  and  Kentucky,  which  separates  it  from  a 
higher  calcareous  horizon  which  has  been  called  Paint  Creek  in  western  Hli- 


UPPER    M1SSISS1PPIAN    SERIES,    CHESTER    GROUP  159 

nois,  and  which  is  equivalent  to  some  portion  of  the  formation  that  Butts 
has  named  Gasper  in  Kentucky.  In  the  Paint  Creek  the  pentremites  occur 
locally  in  enormous  numbers  and  exhibit  a  great  range  of  variation.  The 
Gasper  also  is  a  notable  pentremite  horizon,  and  Ulrich  has  recognized 
essentially  all  of  the  same  species  in  the  two  formations.  Other  faunal  ele- 
ments of  the  Paint  Creek  and  the  upper  Gasper,  and  the  equivalent  of  these 
beds  in  Hardin,  Pope  and  Johnson  counties,  Illinois,  are  in  such  close  con- 
formity that  the  equivalence  of  this  horizon  from  western  Illinois  to  central 
Kentucky  is  supported  by  abundant  evidence.  The  nature  of  this  evidence 
will  be  considered  in  greater  detail  in  the  discussion  of  the  Paint  Creek  form- 
ation in  this  report. 

Bethel  Sandstone 

name  and  general  distribution 

The  Yankeetown  formation  was  originally  described  from  Monroe  and 
Eandolph  counties,  Illinois,  the  type  locality  being  in  the  neighborhood  of 
Yankeetown  School  near  the  southeastern  corner  of  the  first  of  these  counties. 
It  is  a  very  persistent  unit  in  the  Chester  succession  of  western  Illinois, 
although  it  is  not  of  great  thickness.  The  formation  has  been  traced  con- 
tinuously from  northern  Perry  County,  Missouri,  through  the  southeastern 
corner  of  Ste.  Genevieve  County  of  the  same  state,  northward  into  Illinois 
across  Eandolph  and  Monroe  counties  and  into  St.  Clair  County,  where  it 
passes  beneath  the  Pennsylvanian  formations.  Throughout  this  region  the 
formation  probably  nowhere  exceeds  twenty  feet  in  thickness,  and  in  places 
it  is  considerably  less.  It  is  everywhere  a  siliceous  formation,  many  of  the 
surface  exposures  being  essentially  chert.  In  most  localities,  however,  the 
chert  is  more  or  less  sandy  in  bands  and  streaks,  and  in  places  it  is  essentially 
a  quartzite. 

When  Engelmann  described  the  Chester  section  of  southern  Illinois1,  he 
recognized  an  alternating  succession  of  sandstones  and  limestones  which  were 
numbered  from  the  highest  to  the  lowest,  the  odd  numbers  being  limestones 
and  the  even  ones  sandstones.  He  believed  that  his  two  lowest  divisions,  Nos. 
9  and  10,  were  not  widely  distributed,  but  he  especially  called  attention  to  the 
lowest  sandstone,  No.  10,  and  its  superjacent  limestone  in  the  Cache  Eiver 
bluff  of  Johnson  County,  at  Indian  Point  south  of  Vienna2,  resting  on  what 
he  believed  to  be  St.  Louis  limestone.  Field  studies  of  the  last  few  years 
have  shown  that  the  limestone  in  this  section  that  Engelmann  believed  to  be 
St.  Louis  is  really  the  upper  part  of  the  Eenault;  his  sandstone  No.  10  there- 
fore, occupies  the  position  of  the  Yankeetown,  and  his  limestone  No.  9  is  the 
Paint  Creek.     In  Hardin  County,  however,  the  Chester  sandstone  designated 

1  Trans.   St.   Louis  Acad.   Sci.,  vol.   2,  pt.   1,  p.   189,    (1863). 
2Geol.  Surv.  Illinois,  vol.  I,  p.  380,    (1866). 


160  GEOLOGY    OF    HARDIN    COUNTY 

as  No.  10  by  Engelmann  has  proven  to  be  the  Rosiclare,  and  limestone  No.  9 
was  the  "Lower  Ohara/?  Shetlerville  and  Eenault  together,  and  the  true 
equivalent  of  his  No.  10  in  Johnson  County  was  included  in  sandstone  No.  8, 
to  which  he  had  applied  the  name  Cypress.  The  recent  field  work  has  clearly 
established  the  fact  that  the  sandstone  referred  to  by  Engelmann  as  No.  8 
or  Cypress  in  Hardin  County,  includes  two  sandstone  units  with  a  shale 
formation  between,  and  that  the  uppermost  of  these  sandstone  units  alone 
is  the  Cypress;  that  the  shale  member,  with  some  limestone  plates,  is  the 
equivalent  of  Engelmann' s  No.  9  in  the  Johnson  County  section;  and  conse- 
quently that  the  lower  sandstone  member  occupies  the  position  of  No.  10  in 
the  Johnson  County  section  which  is  the  horizon  of  the  Yankeetown.  In 
Hardin  and  Pope  counties  and  southward  into  Kentucky,  this  lower  sand- 
stone is  a  massive  formation  at  least  100  feet  thick  in  places,  very  different 
in  this  respect  from  the  thin,  chert-like  typical  Yankeetown,  and  furthermore 
it  is  known  that  the  siliceous  deposits  at  this  horizon  are  locally  lacking 
entirely  in  southeastern  Johnson  County.  Butts  has  given  the  name  Bethel1 
to  this  sandstone  formation,  from  a  locality  in  Crittenden  County,  Kentucky, 
and  this  name  may  be  extended  to  Hardin  County.  The  only  reason  for  not 
extending  the  name  Yankeetown  into  Hardin  County  is  the  difference  in 
lithologic  character  and  the  fact  that  the  deposit  is  not  certainly  known  to 
continue  uninterruptedly  from  Randolph  to  Hardin  counties. 

The  Bethel  sandstone  can  everywhere  be  recognized  in  Hardin  County, 
from  the  fact  that  it  is  the  first  of  the  sandstones  of  importance  coming  into 
the  general  geological  section  above  the  great  predominantly  limestone  mass, 
including  downward  the  Renault,  Shetlerville,  Ste.  Genevieve,  St.  Louis, 
Warsaw,  and  Osage,  in  all  1,400  or  1,500  feet,  extending  from  the  base  of  the 
Bethel  down  to  the  top  of  the  Chattanooga  shale.  In  this  entire  thickness  the 
inconspicuous  Rosiclare  sandstone,  5  to  20  feet  thick,  60  to  100  feet  below 
the  Bethel,  is  the  only  persistent  sandstone  formation. 

The  Bethel  sandstone  is  nearly  everywhere  a  bluff-forming  bed,  rising 
more  or  less  abruptly  above  the  easily  broken  clown  Renault  and  Shetlerville 
formations,  which  are  very  commonly  covered  by  Bethel  sandstone  talus.  The 
distribution  of  the  formation  follows  closely  that  of  the  underlying  Renault 
in  all  three  of  the  structural  areas  of  the  county  that  have  been  described 
(see  figure  3).  In  the  southeastern  portion  of  the  county  the  Bethel  outcrops 
in  a  line  of  bluffs  starting  at  the  Ohio  River  bottoms  a  little  over  two  miles 
east  of  Cave  in  Rock,  and  extending  in  a  northwesterly  direction  to  sec.  33, 
T.  11  S.,  R.  9  E.,  where  it  is  interrupted  by  the  Peters  Creek  fault,  which 
limits  the  central  faulted  zone.  Throughout  the  extent  of  this  outcrop  the 
strata,  dip  to  the  northeast,  so  that  from  the  summit  of  the  sandstone  bluff  a 
dip  slope  underlain  by  the  formation  extends  for  some  distance  down  the  dip. 

1Miss.  Form,  of  W.  Ky.,  p.  63,    (1918). 


UPPER    MISSISSIPPI  AN    SERIES,    CHESTER    GROUP  161 

From  sec.  33,  the  Bethel  sandstone  outcrop  continues  in  a  southwesterly 
direction  in  the  line  of  bluffs  which  continue  to  Big  Creek,  one  and  one-half 
miles  northwest  of  Elizabethtown.  Farther  to  the  southwest  the  Bethel  caps 
the  two  summits  of  the  isolated  hill  which  rises  from  the  Ohio  Eiver  bank,  just 
below  Eosiclare. 

In  the  complexly  faulted  belt  number  two  of  the  faulted  zone,  lying 
northwest  and  west  of  Elizabethtown,  the  outcrops  of  the  Bethel  sandstone 
are  much  scattered  and  occupy  comparatively  small  areas.  One  such  area  lies 
upon  each  side  of  Hosick  Creek  from  half  a  mile  to  a  mile  north  of  Bassett 
School.  A  number  of  small  patches  of  the  sandstone  are  present  less  than 
a  mile  north  of  the  iron  bridge  over  Big  Creek  near  Elizabethtown.  A  some- 
what larger  area  is  present  in  the  hills  southeast  of  the  mouth  of  Hogthief 
Creek,  and  still  another  small  area  occupies  the  summit  of  the  hill  just  south 
of  Stone  School.  In  the  extreme  southwestern  part  of  the  county  the  Bethel 
occupies  a  portion  of  an  irregularly  outlined  fault  block  east  of  Wallace 
Branch  and  about  two  miles  above  its  mouth.  West  of  Wallace  Branch  this 
sandstone  forms  the  summit  of  Melcher  Hills  and  of  a  number  of  smaller 
elevations  between  those  hills  and  the  Shetlerville  fault.  West  of  the  Shetler- 
ville  fault  the  Bethel  formation  extends  to  the  Hardin-Pope  county  line,  and 
in  the  Ohio  Biver  bluffs  at  and  on  either  side  of  the  county  line  there  is  a 
most  excellent  exposure  of  the  sandstone  which  exhibits  a  greater  thickness 
than  does  any  other  outcrop  in  the  county. 

In  the  more  northern  part  of  belt  one  of  the  central  faulted  zone,  the 
Bethel  sandstone  occupies  a  belt  extending  from  sec.  26,  T.  11  S.,  B.  8  E.,  in 
a  general  easterly  or  northeasterly  direction  to  sec.  20,  T.  11  S.,  B.  9  E.  Near 
the  middle  point  of  this  line  of  outcrop  the  formation  is  slightly  offset  by  a 
fault  extending  in  a  northeast-southwest  direction.  West  of  this  interrupting 
fault  the  formation  occupies  its  normal  position  in  the  stratigraphic  sequence, 
but  to  the  east  it  is  limited  by  a  more  oblique  northeast-southwest  fault  which 
brings  it  into  fault  contact  with  considerably  younger  Chester  formations. 

In  the  northwestern  part  of  the  county  the  Bethel  occupies  its  normal 
position  in  the  stratigraphic  sequence  in  a  narrow  outcrop  extending  from 
the  Hardin-Pope  county  line  to  a  point  a  short  distance  southwest  of  Lees 
Mine  where  the  outcrop  is  offset  for  a  little  over  one  mile  to  the  southwest  by 
the  Lee  fault.  From  this  fault  the  outcrop  of  the  formation  continues  in  a 
southeasterly  direction  to  the  Wolrab  Mill  fault,  although  it  is  slightly  inter- 
rupted by  a  short  fault  running  a  little  west  of  north  through  sec.  23,. T.  11 
S.,  B.  8  E. 

LITHOLOGIC    CHARACTER 

The  Bethel  sandstone  is  fine-grained,  massive,  and  compact,  and  is  com- 
monly more  or  less  irregularly  cross-bedded.    Tt  is  rather  uniform  in  texture 
—n  G 


162  GEOLOGY    OF    HAEDIN    COUNTY 

although  locally  a  few  streaks  of  quartz  pebbles  the  size  of  peas,  have  been 
observed.  Upon  the  weathered  surfaces  it  is  }rellow  or  yellow-brown  in  color, 
.  becoming  reddish-brown  locally.  Unweathered  surfaces  of  the  rock,  when 
freshly  broken  into,  are  lighter  colored  than  the  long  exposed  surfaces,  in 
some  places  being  nearly  white.  Not  infrequently  such  surfaces  exhibit  a 
strongly  mottled  appearance,  brown  spots  having  diameters  up  to  one-tenth 
of  an  inch  being  thickly  scattered  through  the  lighter  portion.  Neither  in 
this  county,  nor  in  the  surrounding  region  in  Illinois  and  elvntucky,  does  the 
Bethel  exhibit  the  distinctly  cherty  phase  which  is  so  characteristic  of  the 
Yankeetown  in  the  Mississippi  River  counties.  Both  formations,  however,  are 
essentially  siliceous,  the  western  one  being  a  sandy  chert,  quartzitic  in  places, 
while  the  southeastern  is  a  sandstone. 

DETAILED    SECTIONS 

No  significant  detailed  sections  across  the  horizon  of  the  Bethel  sandstone 
have  been  measured  in  Hardin  County,  but  a  number  of  sections  in  Pope  and 
Johnson  counties  which  have  an  important  bearing  upon  the  interpretation  of 
the  formation  in  southeastern  Illinois,  may  be  recorded  here.  The  first  of 
these  is  the  section  already  mentioned,  in  the  Cache  River  bluffs  six  miles 
south  of  Vienna  at  Indian  Point,  in  southern  Johnson  County. 

Section  at  Indian  Point,  Johnson  County,  Illinois,  in  sec.  32,  T.  IS  8.,  R.  3  E. 

Feet 

5.  Sandstone,  massive,  moderately  coarse,  yellow-brown  in  color,  with  fer- 
ruginous seams,  cross-bedded,  with  numerous  fragments  of  plant  stems. 
Chester  bed  No.  8,  or  Cypress  sandstone  of  Engelmann's  section 30 

4.  Limestone  and  shale  interbedded,  mostly  talus-covered,  with  slabs  of  lime- 
stone, an  occasional  outcropping  limestone  ledge.  Fossiliferous.  Over 
much  of  the  slope  this  bed  is  completely  covered  by  the  sandstone  talus. 
Bed  No.  9  of  Engelmann's  section 

3.  Sandstone,  irregularly  thin-bedded,  cross-bedded  in  part,  with  some  thin 
shaly  partings.  Fine-grained,  yellow-brown  in  color,  more  or  less  cal- 
careous.    No.   10  of  Engelmann's  section 

2.  Limestone,  arenaceous,  with  thin,  discontinuous  sandy  partings,  the  lower 
six  inches  conglomeratic,  with  angular  limestone  pebbles,  the  contact 
with  the  bed  below  uneven 1 

1.     Limestone,   oolitic   or  crystalline,  much   of  it  strongly  cross-bedded,  light 

gray  in  color.     Fossiliferous.     Exposed 12 

In  this  section  the  limestone  bed  No.  1  carries  the  characteristic  Talaro- 
crinus  fauna  of  the  Renault.  Beds  2  and  3  together  occupy  the  horizon  of  the 
Yankeetown  and  Bethel,  beds  4  and  5  being  respectively  the  Paint  Creek 
and  Cypress. 

Another  section  in  which  the  Bethel  is  well  exhibited  is  in  the  Ohio  River 
bluff  at  Birds  Point,  north  of  Bay  bottoms,  about  four  and  one-half  miles 
below  Golconda,  in  Pope  County. 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER    GROUP  163 

Section  at  Birds  Point,  Pope  County 

Feet 
6.  .  Sandstone,  fine-grained,  massive,  yellow-brown  in  color.    The  Cypress  sand- 
stone         70 

5.     Talus-covered,  probably  a  continuation  of  the  shale  below 20 

4.     Shale,  bluish  to  gray  in  color,  thinly  laminar  and  fissile 15 

3.     Sandstone,  moderately  fine-grained,  yellowish-brown  in  color,  massive  be- 
low, becoming  somewhat  shaly  towards  the  top 45 

2.     Talus-covered    80 

1.     Limestone,  hard,  bluish-gray  in  color,  with  Talarocrinus  fauna  of  the  Re- 
nault.    Exposed 5 

In  this  section  the  sandstone  bed  No.  3  is  the  Bethel  sandstone. 

STRATIGRAPHIC    RELATIONS 

The  actual  contact  of  the  Bethel  sandstone  upon  the  subjacent  Renault  is 
well  exhibited  in  the  bluffs  east  of  Cave  in  Rock,  at  the  locality  that  has 
already  been  described  in  the  discussion  of  the  stratigraphic  relations  of  the 
Renault  (see  figures  11  and  12).  Again  in  the  Cache  Eiver  bluff  section  in 
Johnson  County,  which  has  already  been  described  in  detail,  the  actual  basal 
contact  of  the  sandstone  occupying  this  horizon  is  clearly  exposed  in  the  Bur- 
lington railroad  cut  at  that  point.  This  contact  line  between  the  Eenault 
below  and  the  overlying  sandstone  is  irregular  and  undulating,  and  the  base 
of  the  higher  formation  includes  a  conglomeratic  layer,  all  of  which  goes  to 
show  that  the  higher  formation  lies  unconformably  upon  the  Renault,  and  an 
unconformity  between  the  two  formations  is  certainly  present  continuously 
throughout  southeastern  Illinois  and  the  adjacent  portion  of  Kentucky.  The 
contact  line  between  the  Bethel  and  the  overlying  Paint  Creek  formation  has 
been  observed  at  no  point  within  the  region  under  consideration.  In  the 
section  at  Birds  Point  in  Pope  County,  four  and  one-half  miles  below  Gol- 
conda,  described  above,  the  upper  portion  of  the  Bethel  seems  to  become  shaly 
in  character,  which  suggests  a  gradation  from  the  sandstone  into  the  overlying 
shales  without  unconformity.  Elsewhere,  however,  conglomeratic  beds  have 
been  observed  at  a  number  of  localities  at  the  base  of  the  Paint  Creek,  which 
would  suggest  an  unconformity  at  this  horizon. 

THICKNESS 

The  thickness  of  the  Bethel  sandstone  in  southeastern  Illinois  is  some- 
what variable.  In  the  Cache  River  bluff  section  in  southern  Johnson  County, 
twelve  feet  of  sandstone  equivalent  to  the  Yankeetown  and  Bethel  is  exposed,  a 
thickness  that  is  comparable  with  that  in  the  typical  Yankeetown  exposures 
in  Monroe  and  Randolph  counties.  There  are  places  in  southeastern  Johnson 
County  where  the  formation  is  lacking  entirely,  but  to  the  east,  across  Pope 
and  into  Hardin  County,  the  formation  becomes  thicker  and  takes  upon  itself 


164  GEOLOGY    OF    HARDIN    COUNTY 


the  typical  characteristics  of  the  Bethel.  In  the  river  bluff  below  Golconda, 
in  Pope  County,  an  interval  of  approximately  50  feet  is  occupied  by  the 
Bethel.  In  the  Birds  Point  section  four  and  one-half  miles  below  Golconda, 
45  feet  of  Bethel  sandstone  is  exposed,  but  the  talus-covered  interval  of  80 
feet  between  the  sandstone  and  the  first  outcrop  of  Renault  limestone,  makes 
possible  a  somewhat  greater  thickness  for  the  formation.  The  usual  thickness 
of  the  formation  through  Hardin  County  may  be  assumed  to  be  approximately 
50  or  60  feet,  although  in  places,  as  in  the  river  bluff  below  Shetlerville  it  is 
certainly  greater  than  this,  being  at  least  100  feet. 

PALEONTOLOGY 

Although  imperfect  fossil  remains  of  various  sorts  can  be  detected  in 
the  Bethel  sandstone  in  some  places  in  Hardin  County,  no  good  fossils  have 
been  observed.  The  fragments  which  have  been  met  with  are  brachiopods 
and  bryozoans  of  common  Chester  types,  among  which  may  be  mentioned  axes 
of  Archimedes,  productoid  shells,  probably  Diaphragmus,  and  Reticularia 
setigercb.  Besides  these  invertebrates,  fragments  of  plant  stems  are  commonly 
met  with. 

CORRELATION 

The  correlation  of  the  Bethel  sandstone  in  southeastern  Illinois  with  the 
Yankeetown  of  Monroe  and  Eandolph  counties,  is  based  upon  the  stratigraphic 
position  of  the  beds  in  the  two  regions.  In  both  of  the  regions  the  under- 
lying and  overlying  formations  are  calcareous  with  many  fossils,  and  their 
correlation  is  established  by  abundant  paleontological  evidence,  which  in  turn, 
gives  sufficient  basis  for  the  establishment  of  the  equivalency  of  the  beds  lying 
between  the  fossiliferous  horizons  in  the  two  regions. 

In  the  earlier  treatment  of  the  Hardin  County  section  by  Engelmann1, 
the  Rosiclare  sandstone  of  the  Ste.  Genevieve  formation  was  believed  to  be  the 
equivalent  of  Bed  No.  10  of  the  Chester  section  of  Johnson  County,  and  in 
consequence  of  this  incorrect  correlation  he  included  the  Bethel  sandstone 
of  this  county  in  his  sandstone  No.  8,  to  which  he  had  applied  the  name 
Cypress.  The  real  importance  of  the  Paint  Creek  shale  in  the  Hardin  County 
section  was  not  appreciated  by  Engelmann,  and  he  seems  to  have  believed  it 
to  be  a  shale  member  in  his  Cypress  sandstone. 

Paint  Creek  Formation 

name  and  distribution 

The  Paint  Creek  formation  was  originally  described  from  Monroe  and 
Randolph  counties,  Illinois,  where  it  is  closely  associated  with  the  underlying 

iGeol.   Surv.  of  111.,  vol.   1,  pp.    350-375    (1886),  also  Econ.  Geol.  111.,  vol.   1,  PP-   291" 
319,    (1882). 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  165 

Tankeetown  formation.  The  distribution  of  the  formation  in  the  Mississippi 
Valley  is  essentially  the  same  as  that  of  the  subjacent  formation,  extending 
northward  from  northern  Perry  and  southeastern  Ste.  Genevieve  counties, 
Missouri,  across  Mississippi  River  into  Illinois,  where  the  outcrop  of  the 
formation  extends  across  Randolph  and  Monroe  counties  and  continues  into 
St.  Clair  County. 

Beyond  the  region  of  its  typical  development,  the  Paint  Creek  formation 
is  well  exhibited  in  southeastern  Illinois,  and  continues  southward  into  Ken- 
tucky where  it  is  represented  by  some  portion  of  the  Gasper  limestone.  In 
the  Cache  River  section  in  southern  Johnson  County,  Illinois,  Engelmann 
designated  the  Paint  Creek  as  Bed  No.  9  of  the  Chester  group,  but  his  Bed 
Xo.  9  in  Pope  and  Hardin  counties  included  the  Renault,  Shetlerville,  and 
"Lower  Ohara,"  because  of  his  mistaken  correlation  of  the  Rosiclare  sand- 
stone with  Bed  Xo.  10  in  the  Johnson  County  section. 

In  Hardin  County  the  Paint  Creek  shale  is  present  in  a  number  of  more 
or  less  isolated  areas  within  the  central  faulted  region,  but  it  is  inadequately 
exposed  in  every  one  of  these  localities.  Perhaps  the  best  exposure  in  this 
part  of  the  county  is  in  the  XE.  14  NE.  %  sec.  21,  T.  12  S.,  R.  8  E1.,  about 
three-fourths  of  a  mile  north  of  the  iron  bridge  over  Big  Creek  between  Eliza- 
bethtown  and  Rosiclare.  In  the  hills  extending  northeast  from  this  locality 
the  Paint  Creek  is  undoubtedly  present  wherever  the  proper  portion  of  the 
geological  section  constitutes  the  surface  rock,  but  it  is  for  the  most  part  more 
or  less  completely  covered.  The  presence  of  the  formation  may  be  determined 
in  places  by  fragments  of  shale  in  the  wash  of  gullies  or  small  streams,  and 
elsewhere  by  topographic  depressions  or  sags  in  the  surface  indicating  the 
presence  of  a  soft  formation  much  more  easily  broken  clown  than  the  resistant 
sandstones  which  occur  both  below  and  above  the  shale.  Fragments  of  Paint 
Creek  shale  are  met  with  in  the  point  of  the  hill  nearly  clue  north  of  Bassett 
School  (north  of  Elizabethtown)  and  the  northwest  slope  of  the  hill  extend- 
ing from  near  the  middle  of  the  south  line  of  sec.  12,  T.  12  $.,  R.  8  E.,  to  the 
middle  of  the  north  line  of  sec.  7,  T.  12  S'.3  R.  9  E.,  is  covered,  in  sec.  12  at 
least,  with  the  shale,  dipping  rather  steeply  to  the  northwest.  The  shale  is 
well  exposed  in  the  bank  of  the  shallow  ravine  heading  just  north  of  the 
house  on  the  point  of  this  ridge  just  north  of  the  south  line  of  sec.  12.  Another 
locality  where  this  shale  formation  is  present  within  the  median  faulted  zone 
of  the  county,  is  in  the  hill  southeast  of  the  junction  of  Hogthief  Creek  with 
Big  Creek,  in  sec.  9,  T.  12  S.,  R,  8  E.,  and  extending  eastward  into  the  edge 
of  the  adjoining  sec.  10.  In  this  area  the  shale,  along  with  the  other  forma- 
tions, dips  to  the  southwest.  Xo  good  outcrops  of  the  formation  have  been 
observed  in  this  area,  but  the  underlying  Bethel  sandstone  is  well  exposed  and 
at  a  number  of  points  the  presence  of  the  calcareous  beds  of  the  shale  is  sug- 
gested by  the  characteristic  red  clay  residuum  of  the  formation. 


166  GEOLOGY   OF   HAKD-IN    COUNTY 

Outside  of  the  central  much-faulted  zone  of  the  county,  the  Paint  Creel 
formation  is  present  in  the  northwestern  part,  where  it  occupies  its  propei 
position  in  the  stratigraphic  sequence.  One  of  the  best  exposures  of  the  shale 
in  the  whole  county  is  in  the  bed  of  a  small  tributary  of  Pinhook  Creek, 
running  northwest  across  the  SW.  14  sec.  7,  T.  11  S.,  K.  8  E.,  about  two  miles 
north  of  Hicks.  The  formation  is  fully  exposed  in  the  bed  of  Buck  Creek  in 
the  SW.  14  sec.  34,  T.  11  S.,  E.  7  E.  At  both  of  these  places  the  position  of 
the  shale  between  the  Bethel  sandstone  below  and  the  Cypress  sandstone  above 
is  clearly  exhibited,  both  sandstones  being  exposed  at  each  locality.  At  the 
last  described  locality,  the  side  ravine  extending  southwest  to  the  corner  of 
the  section,  and  the  one  on  the  northeast  side  of  the  main  ravine  running  up 
to  Pinhook  School,  are  eroded  on  the  shale,  and  so  also  the  hollow  heading 
near  the  road  on  the  line  between  sections  8  and  9,  about  three-fourths  of  a 
mile  southwest  of  Karbers  Eidge  and  extending  northwestward  to  Pinhool 
Creek.  These  ravines  are  examples  of  the  fact  stated  above,  that  the  outcro] 
of  the  Paint  Creek  shale  is  in  places  marked  by  low  ground  or  hollows.  Th( 
Paint  Creek  is  well  exposed  for  a  long  distance  along  the  ravine  in  the  NE.  14 
sec.  26,  T.  11  S.,  E.  8  E.,  one-half  mile  northeast  of  Gross,  and  in  the  shallow 
ravine  just  below  the  private  road  in  sec.  21,  T.  11  S.,  E.  8  E.,  and  near  th( 
center  of  its  east  line. 

In  the  southeastern,  unfaulted  portion  of  the  county,  the  Paint  Creek 
shale  is  well  exposed  in  the  ravine  heading  near  the  center  of  sec.  34,  T.  11  S., 
E.  9  E.,  and  in  the  mouth  of  the  north-south  ravine  nearly  opposite  the  on( 
last  mentioned.  The  shale  is  not  over  twenty  feet  thick  at  these  last  two 
localities  and  seems  to  contain  some  rather  thick  sandstone  layers  which  may 
indicate  that  the  formation  is  changing  into  sandstone  in  this  direction.  In  a 
southeastward  direction  from  the  localities  just  mentioned  the  Paint  Creel 
seems  to  be  persistent  to  the  southeast  corner  of  sec.  6,  T.  12  S.,  E.  10  E., 
beyond  which  point  the  formation  has  not  been  observed  and  probably  is  not 
present.  At  this  last  exposure  where  the  shale  has  been  observed  the  following 
section  has  been  studied  by  Mr.  Butts : 

Section  near  the  center  of  the  SE.  y±  sec.  6,  T.  12  S.,  R.  JO  E. 

Ft. 
9.     Sandstone,  massively  bedded    ledge-maker,    bottom    of    Cypress  sand- 
stone         10 

8.     Not  exposed,  perhaps  shale 5 

7.     Sandstone,  laminated,  coarse,  micaceous,  whitish .       2         6 

6.     Shale,  blue    1 

5.     Sandstone    

4.     Clay,  probably  residuum  from  shale 1 

3.     Sandstone,  thin-bedded 2 

2.     Not   exposed 4 

1.     Sandstone,  flaggy    40 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  16?' 

The  conditions  in  a  southeastward  direction  from  the  section  just  de- 
■  scribed  may  be  interpreted  in  two  ways.  Either  the  Paint  Creek  thins  out 
entirely,  allowing  the  Cypress  sandstone  to  rest  directly  upon  the  Bethel,  or 
the  Paint  Creek  undergoes  a  change  in  character  from  mainly  shale  to  more 
or  less  thinly  bedded  sandstones.  At  any  rate,  beyond  this  point  there  is  a 
continuous  succession  of  sandstone  beds  between  the  Renault  and  Grolconda 
limestones,  which  approximate  the  united  thickness  of  the  Bethel  and  the 
Cypress  sandstones,  both  of  which  formations  may  be  considered  as  being 
!  represented  in  the  entire  mass.  At  about  the  horizon  where  the  Paint  Creek 
shale  should  be  present  there  are  layers  of  sandstone  more  thinly  bedded  than 
either  the  beds  above  or  below.  In  the  mapping  of  this  portion  of  the  county 
it  has  been  considered  that  the  Paint  Creek  is  not  present,  and  the  Cypress- 
sandstone  is  shown  resting  upon  the  Bethel,  the  boundary  between  the  two- 
formations  being  drawn  as  nearly  as  possible  at  the  horizon  of  the  thinly 
bedded  sandstone.  It  must  be  recognized  that  this  line  is  placed  more  or  less 
arbitrarily,  and  no  decision  has  been  reached  as  to  whether  the  thinly  bedded 
,  layers  should  be  included  with  the  lower  or  with  the  higher  sandstone  forma- 
tion. 

LITHOLOGIC    CHARACTER 

The  typical  Paint  Creek  is  a  calcareous  formation  with  varying  amounts 
|  of  shale  included  with  the  limestone,  in  the  different  sections.  In  Monroe  and 
Randolph  counties  where  the  Paint  Creek  was  originally  defined,  a  very 
characteristic  member  of  the  formation  is  a  bed  of  deep  red,  non-laminated 
clay  about  fifteen  feet  thick,  in  its  lower  portion.  Above  this  the  shales  are 
more  or  less  calcareous  and  finally  pass  up  into  good  beds  of  limestone  with 
shale  partings.  In  the  Johnson  County  section  the  red  clay  member  of  the 
Paint  Creek  is  wanting,  although  some  variegated  shales  are  present.  The 
lower  portion  of  the  formation  in  Johnson  County  seems  to  be  mostly  shales, 
passing  upward  into  alternating  beds  of  shale  and  limestone.  Some  of  the 
limestone  ledges  are  three  or  four  feet  thick,  but  the  whole  formation  is  so 
heavily  talus-covered  that  its  details  are  not  exhibited  in  any  of  the  outcrops 
that  have  come  under  observation.  In  Pope  and  Hardin  counties  the  forma- 
tion is  made  up  even  more  largely  of  shales  than  in  Johnson  County.  The 
bulk  of  the  rock  is  soft,  dark,  clay  shale,  and  very  thinly  laminated,  very  fine- 
grained sandstone,  the  latter  breaking  up  characteristically  into  small  chips 
which  are  scattered  in  abundance  over  the  weathered  outcrops.  In  some 
j  exposures,  only  shales  have  been  observed,  but  elsewhere  there  are  thin,  platy 
layers  or  discontinuous  lenses  of  impure,  siliceous  limestone  which  contain 
some  imperfectly  preserved  fossils.  At  the  locality  north  of  the  iron  bridge 
between  Elizabethtown  and  Rosiclare,  which  has  already  been  mentioned, 
| masses  of  one  or  more  thin  layers  of  rotten,  ferruginous  sandstone,  with  im- 
perfectly preserved  fossils,  are  scattered  over  the  talus-covered  outcrop.    These 


168  GEOLOGY  OF  HARDIN  COUNTY 

apparent  sandstone  layers  were  doubtless  calcareous  in  their  unweathered 
condition,  but  the  calcareous  matter  has  been  leached  out  where  the  weathered 
rocks  occur.  The  clay  shale  is  dark  in  color,  being  nearly  or  quite  black  where 
it  is  exposed  along  stream  courses  and  is  kept  moist.  It  is  thinly  laminar  in 
structure.  Where  the  shale  is  exposed  in  bluff  faces  it  is  commonly  lighter 
colored,  being  bluish-gray  or  slightly  greenish,  and  on  weathering  it  breaks 
into  flaky  bits.  At  the  locality  north  of  the  bridge  over  Big  Creek  between 
Elizabethtown  and  Iiosiclare,  there  are  numerous  blocks  of  limestone  con- 
glomerate in  the  shale  talus,  which  seem  to  have  come  from  the  base  or  near 
the  base  of  the  Paint  Creek  shale.  Locally  where  this  formation  is  present 
but  is  more  or  less  completely  covered  with  superficial  deposits,  its  presence 
is  indicated  by  the  characteristic  red  clay  residuum  which  is  commonly 
derived  from  such  deposits. 

Southward  from  Hardin  County  the  shaly  character  of  the  Paint  Creek 
persists  into  Crittenden  Count}',  Kentucky,  but  beyond,  in  Caldwell  and 
Christian  counties  of  the  same  state  the  formation  becomes  more  calcareous, 
becoming  a  conspicuous  limestone  formation  with  oolitic  beds,  and  is  the 
upper  member  of  the  formation  to  which  Uirich  originally  gave  the  name 
Tribune  limestone.  Late  observations  however,  have  shown  that  this  name 
was  unfortunately  chosen,  and  that  the  limestone  at  Tribune  is  of  quite  a 
different  age,  and  the  name  Gasper  has  been  substituted.  In  view  of  the  fact 
that  it  is  clearly  the  same  horizon  from  St.  Clair  County,  Illinois,  to  central 
Kentucky,  and  that  throughout  its  extent  it  is  one  of  the  calcareous  members 
of  the  Chester  group,  the  use  of  the  same  formation  name  for  the  unit  through- 
out is  highly  desirable  for  the  sake  of  uniformity  in  nomenclature. 

DETAILED    SECTIONS 

The  most  significant  detailed  sections  including  the  Paint  Creek  forma- 
tion, and  showing  its  stratigraphic  relations  in  southeastern  Illinois,  are  nol 
in  Hardin  County,  but  in  Pope  and  Johnson  counties  farther  west.  The  fol- 
lowing section  in  the  river  bluff  just  below  Golconda  exhibits  the  Paint  Creel 
as  it  is  commonly  developed  in  Hardin  County : 

Section  in  Ohio  River  bluff  below  Golconda 

Fa 

5.  Sandstone,  fine-grained,  yellowish-brown  in  color,  only  the  basal  portion 
well  exposed  at  this  point,  nearly  the  entire  thickness  much  better  ex- 
posed at  the  point  of  the  bluff  at  the  south  side  of  Lusk  Creek  valley. .  .     6( 

4.     Sandstone  and  shale,  not  well  exposed,  largely  talus  covered;  an  arenaceous 

shale  bed  about  five  feet  thick  exposed  about  twelve  feet  below  the  top.  .     3( 

3.  Shale,  greenish  in  color,  argillaceous  or  somewhat  sandy.  Near  the  middle 
of  the  bed  are  some  thin,  lenticular,  arenaceous  limestone  beds,  com- 
monly one  or  two  inches  thick,  with  fossils 3( 

2.     Unexposed;  talus  composed  largely  of  sandstone  slabs 1L 

1.  Sandstone,  massive  ledges  similar  in  character  to  that  at  summit  of  sec- 
tion, exposed  at  this  point 1< 


UPPER    MISSISSIPPI  AN    SERIES,    CHESTER   GROUP  1G9 

In  this  section,  bed  No.  3  is  the  Paint  Creek,  exhibiting  a  thickness  of  30 
feet.  It  is  certainly  thicker  than  this,  however,  for  the  intervals  both  above 
and  below  the  shale  exposure  are  talus  covered,  so  that  neither  of  the  contacts 
of  the  formations  can  be  seen.  Below  the  sandstone  in  the  quarry  at  the 
point  of  the  bluff  below  the  boat  landing  at  Golconda,  about  40  feet  of  the 
shale  is  exposed,  which  seems  to  be  essentially  the  full  thickness  of  the  forma- 
tion at  that  point. 

One  of  the  most  significant  of  the  southeastern  Illinois  sections  of  the 
Paint  Creek  is  that  in  the  Cache  River  bluffs  in  southern  Johnson  County, 
which  has  been  described  in  the  discussion  of  the  Bethel  sandstone  on  a 
previous  page  of  this  chapter.  The  importance  of  the  section  is  in  the  fact 
that  the  beds  at  this  locality  are  abundantly  fossiliferous,  while  the  exposures 
in  Pope  and  Hardin  counties  are  rarely  fossiliferous,  and  the  fossils  which 
have  been  collected  are  commonly  poorly  preserved. 

THICKNESS 

One  of  the  best  exposures  from  which  to  estimate  the  thickness  of  the 
Paint  Creek  shale  is  in  the  section  at  Birds  Point  in  the  Ohio  River  bluffs, 
four  and  one-half  miles  below  Golconda  in  Pope  County,  the  section  having 
already  been  given  in  the  discussion  of  the  Bethel  sandstone;  15  feet  of  shale 
are  exposed  with  a  talus-covered  slope  of  20  feet  above,  which  is  doubtless  also 
underlain  by  shale,  making  a  total  thickness  of  approximately  35  feet.  In 
the  river-bluff  section  at  Golconda  described  just  above,  30  feet  of  the  shale 
are  well  exposed,  with  talus-covered  intervals  above  and  below  which  might 
increase  the  thickness  to  50  feet.  The  exposure  below  the  boat  landing  at 
Golconda  is  about  40  feet.  The  observations  in  Hardin  County,  while  less 
definite  than  those  in  the  Pope  County  sections,  accord  with  them  approxi- 
mately in  regard  to  the  thickness  of  the  formation,  and  40  or  50  feet  may  be 
assumed  to  be  the  normal  thickness  of  the  shale  where  it  is  fully  developed. 

STRATIGRAPHIC    RELATIONS 

The  actual  contacts  of  the  Paint  Creek  shale  with  the  underlying  and 
overlying  formations  have  not  been  observed  commonly,  the  nearest  approach 
to  actual  visible  contacts  being  in  the  Buck  Creek  section  and  in  the  ravine 
north  of  Hamp  Mine ;  the  evidence  bearing  upon  the  stratigraphic  relations  of 
the  formation  with  the  adjacent  formations  is  therefore  inconclusive.  The 
most  significant  evidence  met  with  is  the  presence  of  the  limestone  con- 
glomerate layer,  masses  of  which  have  been  observed  in  the  talus  at  the  base 
of  the  shale  about  three-fourths  of  a  mile  north  of  the  iron  bridge  over  Big 
Creek  on  the  Elizabethtown  and  Rosiclare  road.  This  conglomerate  suggests 
a  condition   of   unconformity  between   the  shale   and   the   Bethel   sandstone 


170 


GEOLOGY  OE  HARDIN  COUNTY 


beneath,  but  no  corroborative  evidence  has  been  observed  at  any  other  locality, 
and  for  the  present  the  stratigraphic  relations  between  these  two  formations 
must  be  considered  as  not  certainly  determined. 

The  stratigraphic  relations  between  the  Paint  Creek  and  the  overlying 
Cypress  sandstone  are  also  uncertain.  The  fact  that  the  shale  seems  to  be 
wanting  in  the  southeastern  part  of  the  county  suggests  that  it  may  have  been 
removed  by  erosion  subsequent  to  its  deposition  and  before  the  initiation  of 
the  Cypress  sandstone  deposition,  and  such  an  erosion  interval,  if  it  existed, 
would  be  evidence  to  establish  the  unconformable  relations  between  the  two 
formations.  The  alternative  conclusions  are  that  the  shale  was  never  deposited 
in  the  area  where  it  is  now  wanting,  or  that  it  is  represented  by  thinly  bedded 
sandstone,  which,  perhaps,  is  the  most  probable  explanation. 

PALEONTOLOGY 

In  Hardin  Count}'',  fossils  have  been  rarely  met  in  the  Paint  Creek  shales, 
and  those  that  have  been  seen  are  poorly  preserved.  They  occur  only  in  some 
of  the  thin,  impure  limestone  layers  which  are  locally  present  in  the  forma- 
tion. In  the  bluff  section  at  Golconda  in  Pope  County  (see  page  168)  a  few 
fossils  have  been  collected  in  the  siliceous  limestone  layers  that  are  there 
present,  but  the  most  important  fauna  that  has  been  secured  from  the  forma- 
tion anywhere  in  southeastern  Illinois,  is  from  the  exposure  in  the  Cache 
Elver  bluffs  in  southern  Johnson  County,  described  on  a  previous  page  in  the 
discussion  of  the  Bethel  sandstone.  At  this  locality  there  is  much  more  lime- 
stone included  in  the  formation  than  in  Pope  and  Hardin  counties,  and  in 
consequence  the  fossils  are  more  numerous.  The  complete  fauna  from  this 
locality  so  far  as  it  has  been  collected,  is  as  follows : 


Fossils  from   the  Paint  Creek  formation  collected  at  Indian  Point,   Cache  River 
oluffs,  Johnson  County,  Illinois,  in  sec.  32,  T.  IS  8.,  R.  3  E. 


Triplophyllum      spinulosum       (M.-E. 

and   H.) 
Caninia  n.sp. 

Pentremites  godoni  DeFrance 
Pentremites   pyramidatus   Ulrich 
Pterotocrinus    serratus   n.sp. 
Taxocrinus  sp. 
Pachylocrinns  cashensis  n.sp 
Pachylocrinus    spinuliferus 

(Worthen) 
Hydreionocrinus  sp. 
Decadocrinus    columbiensis 

(Worthen) 
Eupachycrinus    maniformis    (Y.    and' 

S.) 


Archimedes  meekanus  Hall 
Archimedes  proutanus  Ulrich 
Archimedes   cf.   swallovanus   Hall 
Polypora  tuberculata  Prout 
Lyropora   ranosculum   Ulrich 
Thamniscus  furcillatus  Ulrich 
Septopora  subquadrans  Ulrich 
Rhombopora   sp. 
Streblotrypa   nicklesi   Ulrich 
Cystodictya  labiosa  n.sp. 
Glyptopora  punctipora  Ulrich 
Orthotetes     kaskaskiensis      (McChes- 

ney) 
Diaphragmus  elegans    (N.   and  P.) 
Dielasma  illinoisensis  Weller 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  173 

Fistulipora  excelens  Ulricli  Girtyella   indianensis    (Girty) 

Batostomella  sp.  Spiriferina  spinosa   (N.  and  P.) 

Stenopora  tuberculata   (Prout)  Spirifer  increbescens  var.   transvers- 

Lioclema  n.sp.  alis  Hall 

Fenestella  cestriensis  Ulrich  Reticularia  setigera    (Hall) 

Fenestella  serratula  Ulricli  Eumetria  vera   (Hall) 

Fenestella   tenax   Ulricli  Cliothyridina    sublamellosa    (Hall) 

Archimedes  communis  Ulrich  Composita   trinuclea    (Hall) 

Archimedes  compactus  Ulrich  Orthonychia  sp. 
Archimedes   distans   Ulrich 

The  impure  limestone  layers  from  the  section  at  Golconda  have  afforded 
the  following  species : 

Fossils  from  the  Paint  Creek  formation  collected  in   the  Ohio  River  bluff  below 

Golconda 

Fenestella    (several  species)  Eumetria  vera   (Hall) 

Archimedes  sp.  Leda  sp. 

Cystodictya  labiosa  n.sp.  Aviculopecten  sp. 

Glyptopora  cf.  punctipora  Ulrich  Gastropods      (several      small      unde- 

Chonetes  cf.   chesterensis  Weller  termined  species) 

Girtyella  indianensis    (Girty)  Phillipsia  sp. 

Spiriferina  spinosa    (N.  and   P.) 

CORRELATION 

The  one  essential  point  to  be  determined  in  connection  with  the  correla- 
tion of  the  Paint  Creek  formation  in  southeastern  Illinois,  is  the  question  of 
its  identity  with  the  beds  in  Monroe  and  Randolph  counties  to  which  the  name 
was  originally  applied.     Such  a  correlation  is  established  both  upon  the  evi- 
dence of  the  fossils  and  upon  the  evidence  of  the  stratigraphic  succession.     In 
;  both  regions  the  same  type  of  stratigraphic  succession  is  present,  that  is  an 
alternating  series  of  limy  and  sandy  formations,  but  the  sandy  members  of 
1  the  series  are  attenuated  to  the.  west  and  are  consequently  much  less  con- 
|  spicuous  in  the  Monroe  and  Randolph  county  sections.    In  the  sections  of  the 
two  regions  under  consideration  the  beds  which  have  been  termed  Paint  Creek 
in  each,   occupy   equivalent   positions   stratigraphieally,    and   since   both   are 
situated  within  the  limits  of  the  same  basin  of  sedimentation  the  presumption 
is  that  they  are  equivalent  in  age. 

A  comparison  of  the  fossil  faunas  of  the  Paint  Creek  formation  in  the 
region  of  its  typical  development,  with  the  fauna  of  the  Cache  River  bluff 
section  in  southern  Johnson  County,  brings  out  so  many  common  characteris- 
tics that  the  evidence,  added  to  that  of  their  equivalent  stratigraphic  position, 
is  sufficient  to  fully  establish  their  correlation. 

The  Paint  Creek  fauna  has  much  in  common  with  that  of  the  Renault, 
subjacent  to  the  Yankeetown,  but  there  are  certain  elements  which  are  added 


172 


GEOLOGY  OF    HARDIN  COUNTY 


to  the  assemblage  which  make  it  quite  different  in  many  ways.  The  species 
of  Talarocrinus  with  bilobed  base  persists  into  the  Paint  Creek,  and  many  of 
the  bryozoans  and  brachiopods  are  common  to  the  two  faunas.  Among  the 
bryozoans  Cystodictya  labiosa  is  an  important  one  whose  range  is  restricted 
to  the  Shetlerville,  Renault,  and  Paint  Creek.  G-lyptopora  punctipora  is  an- 
other form  having  the  same  range,  but  it  is  less  common  than  the  Cystodictya. 
Crinoids  other  than  Talarocrinm  are  common  in  the  Paint  Creek,  there  being 
a  greater  number  of  known  species  than  in  the  Renault.  The  distinguishing 
paleontological  features  of  the  Paint  Creek  are  found  in  the  addition  to  the 
fauna  of  elements  which  were  not  present  in  the  Renault.  The  Pentremites 
show  a  very  great  expansion,  the  number  of  individuals  and  species  being 
vastly  greater  than  in  the  Renault.  Among  the  crinoids  the  most  notable 
additions  are  several  members  of  the  genus  Pterotocriniis,  commonly  repre- 
sented only  by  the  ''wing  plates/'  and  an  occasional  base  of  Agassizocrinus. 
A  characteristic  form  of  the  Pterotocrinus  "wing  plates"  is  a  flattened,  spatu- 
late  plate,  with  the  outer  border  serrate.  The  most  notable  addition  among 
the  bryozoans  is  the  great  representation  of  the  genus  Archimedes.  This 
genus  was  unusual  in  the  Renault,  being  entirely  wanting  in  many  f annul es, 
and  always  rare  wherever  found;  but  in  the  Paint  Creek  it  is  much  more  com- 
mon, and  at  least  one  species,  Archimedes  compactus,  is  rather  characteristic 
of  the  fauna,  although  it  does  occur  only  rarely  in  some  of  the  higher  forma- 
tions. Lyropora,  represented  by  several  species,  continues  to  be  a  common 
form  as  it  was  in  the  Renault.  Among  the  brachiopods,  perhaps  the  most 
significant  feature  is  the  presence  of  a  species  of  Chonetes.  Members  of  this 
genus  are  unusual  in  the  Chester  faunas  of  the  Illinois  basin,  the  only  species 
known  being  restricted  to  the  Paint  Creek  fauna.  Another  feature  of  the 
fauna  is  the  less  common  occurrence  of  Spiriferina  transversa,  and  the  great 
abundance  of  the  typical  form  of  Spiriferina  spinosa. 

In  the  following  list  the  species  which  have  been  identified  in  the  Paint 
Creek  fauna  at  the  Cache  River  bluff  are  tabulated.  Occurrence  in  the  Paint 
Creek  faunas  of  Monroe  and  Randolph  counties  is  indicated  by  a  cross  in  the 
first  column  to  the  right,  their  presence  in  higher  Chester  faunas  being  indi- 
cated in  the  second  column.  In  the  columns  at  the  left  the  occurrence  of  the 
species  in  the  Renault  and  Shetlerville  faunas,  is  indicated,  and  also  in  the 
Ste.  Genevieve  limestone.  In  case  the  species  is  represented  in  any  of  these 
horizons  by  a  closely  related  form,  its  presence  is  indicated  by  0  instead  of  X. 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER    GROUP 
Table  showing  geologic  range  of  the  Paint  Creek  fauna 


173 


PAINT  CREEK  FAUNA 


X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 


X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

0 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

Triplophyllum  spinulosum 

Caninia  n.sp 

Pentremites  godoni 

Pentremites  pyramidatus 

Pterotocrinus  serratus 

Taxocrinus  sp 

Pachylocrinus  cashensis 

Pachylocrinus  spinuliferus 

Hydreionocrinus  sp 

Decadocrinus  columbiensis 

Eupachycrinus  maniformis 

Fistulipora  excelens 

Batostomella  sp 

Stenopora  tuberculata 

Lioclema  sp 

Fenestella  cestriensis 

Fenestella  serratula 

Fenestella  tenax 

Archimedes  communis 

Archimedes  compactus 

Archimedes  distans 

Archimedes  meekanus 

Archimedes  proutanus 

Polypora  tuberculata 

Lyropora  ranosculum 

Thamniscus  furcillatus 

Septopora  subquadrans 

Rhombopora  sp 

Streblotrypa  nicklesi 

Cystodictya  labiosa 

Glyptopora  punctipora 

Orthotetes  kaskaskiensis 

Diaphragmus  elegans 

Dielasma  illinoisensis 

Girtyella  indianensis 

Spiriferina  spinosa 

Spirifer  increbescens  var.  transversalis 

Reticularia  setigera 

Eumetria  vera 

Cliothyridina  sublamellosa 

Composita  trinuclea 

Orthonvchia  cf.  chesterensis 


174  GEOLOGY  OF  HARDIN  COUNTY 

This  tabulation  shows  that  36  forms  have  been  identified  specifically  in 
the  Cache  River  fauna,  and  of  this  number  all  but  three  are  also  recorded  in 
the  Paint  Creek  fauna  from  the  Mississippi  River  counties  or  in  some  Chester 
fauna  younger  than  the  Paint  Creek.  The  three  species  not  found  in  the 
more  western  faunas  are  all  crinoids,  fossils  that  are  always  likely  to  be  local 
in  their  occurrence,  or  at  least  in  their  preservation  in  such  a  condition  as 
to  permit  their  identification.  Twenty-six  of  the  species  are  also  recorded 
from  the  Renault  and  Shetlerville  formations.  Of  the  ten  species  which  do 
not  occur  in  the  two  subjacent  faunas,  five  are  species  of  bryozoans  belonging 
to  the  genus  Archimedes.  An  examination  of  the  entire  list  from  Cache  River 
shows  the  presence  of  such  bryozoa  as  Cystodictya  labiosa  and  GJyptopora  punc- 
tipora,  forms  which  are  very  characteristic  of  the  lower  Chester  faunas;  but 
their  association  with  numerous  species  of  Archimedes,  and  with  the  "wing 
plates"  of  Pterotocrinus,  and  especially  with  a  form  of  these  "wing  plates" 
with  serrated  margins,  suggests  a  higher  position  than  the  Renault,  this  asso- 
ciation being  exactly  what  is  met  with  in  the  typical  Paint  Creek  fauna.  On 
the  basis  of  this  paleontological  evidence,  supplemented  by  the  stratigraphic 
succession,  the  correlation  of  the  beds  in  the  two  regions  is  made  doubly  sure. 

The  fauna  from  the  limestone  layers  in  the  shale  exposed  in  the  river 
bluff  at  Golconda  also  bears  out  the  correlation  of  the  Paint  Creek  in  south- 
eastern Illinois  with  that  of  Monroe  and  Randolph  counties.  This  fauna,  is 
small  and  the  fossils  are  not  well  preserved,  but  the  bryozoans  Oystodicfi/a 
labiosa  and  Ghjptopora  punctipora  are  quite  certainly  present,  and  axes  of 
Archimedes  are  not  uncommon.  Perhaps  the  most  significant  species  in  the 
fauna,  and  one  of  the  commonest  ones,  is  the  species  of  Chonetes  that  has 
been  compared  with  C.  chest&rensis.  There  can  be  little  doubt  concerning  thp 
identity  of  the  species  which  is  the  only  member  of  the  genus  known  in  the 
Chester  faunas  of  the  Illinois  basin,  and  which  is  wholly  restricted,  so  far 
as  it  is  known,  to  the  fauna  of  the  Paint  Creek  formation  in  the  more  western 
counties.  The  presence  of  Spiriferina  spinosa  in  the  fauna,  rather  than 
S.  transversa,  is  another  feature  to  be  considered.  In  itself  this  occurrence 
might  not  be  of  much  importance,  but  taken  in  connection  with  other  evidence 
it  adds  its  weight  to  the  probability  of  the  correctness  of  the  Paint  Creek 
correlation. 

In  the  extension  of  the  Chester  section  southward  into  Kentucky  the 
interval  between  the  Bethel  sandstone  and  the  Cypress  sandstone  can  be  traced 
into  Caldwell  and  Christian  counties,  but  the  lithologic  character  of  the  beds 
occupying  the  interval  changes  from  shale  with  very  subordinate  limestone 
layers,  such  as  is  present  in  the  Hardin  County  section,  to  an  important  lime- 
stone with  many  fossils.1  This  limestone  constitutes  the  upper  member  of  the 
formation  in  Kentucky  to  which  Ulrich  gave  the  name  Tribune2,  but  this 

1  Butts,  Mississippian  formations  of  western  Kentucky,  pp.   73-75,    (1918). 
2U.  S.  Geol.  Surv.,  Prof.  Paper,  No.  36,  p.  55,    (1905). 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER    GROUP  175 

name  was  unfortunately  chosen,  the  limestone  at  Tribune  being  an  entirely 
different  horizon,  and  belonging  higher  up  in  the  Chester  group.  On  this 
account  the  name  Gasper1  has  been  introduced  by  Butts  to  take  the  place  of 
Tribune.  For  the  sake  of  uniformity  of  nomenclature,  and  in  view  of  the 
undoubted  continuity  of  the  Paint  Creek  formation  from  the  Mississippi 
River  sections  through  southern  and  southeastern  Illinois  and  on  into  Ken- 
tucky and  beyond,  the  name  Paint  Creek  should  be  extended  to  include  the 
upper  member  of  the  so-called  Gasper,  the  lower  Gasper  probably  being 
Renault. 

Cypress  Sandstone 

name  and  general  distribution 

When  Engelmann  elaborated  his  Chester  section  in  the  southern  counties 
of  Illinois,  he  recognized  an  alternating  series  of  limestones  and  sandstones 
which  he  distinguished  by  number,  beginning  with  the  highest,  the  odd  num- 
bers being  applied  to  the  limestones  and  the  even  numbers  to  the  sandstones. 
He  gave  formation  names  to  none  of  the  units  except  sandstone  No.  8,  which 
he  called  the  Cypress  sandstone2  from  outcrops  along  Cypress  Creek  in  Union 
County.  Engelmann  misinterpreted  the  formation  in  Pope  and  Hardin 
counties,  and  included  in  it  the  Bethel  sandstone  as  well  as  the  Paint  Creek 
shales  which  lie  between  the  two  formations.  Most  if  not  all  of  the  outcrops 
of  the  sandstone  No.  8  which  Engelmann  has  referred  to  in  his  Hardin 
County  report,  are  in  reality  exposures  of  Bethel.  The  formation  is  widely 
distributed  across  southern  Illinois  from  Union  to  Hardin  counties,  and  con- 
tinues southward  into  Kentucky  where  Ulrich  designated  it  as  bed  No.  1  of 
the  Birdsville  formation,  misapplying  the  name  Cypress  to  the  Bethel  sand- 
stone of  this  report.  In  tracing  the  Chester  formations  northwest  from  Union 
County  into  the  typical  Randolph  County  area,  the  Cypress  becomes  much 
attenuated  and  is  represented  in  the  section  by  the  sandy  upper  portion  of 
the  Euma  formation  of  that  region,  and  in  view  of  the  observations  made 
across  the  state  it  seems  desirable  to  restrict  the  name  Euma  to  the  sandstone 
beds  alone,  or  rather  drop  the  name  altogether  and  extend  the  use  of  the  name 
Cypress,  adding  the  shaly  and  somewhat  calcareous  beds  of  the  formation  to 
the  underlying  Paint  Creek. 

The  areal  distribution  of  the  Cypress  sandstone  in  Hardin  County  follows 
closely  that  of  the  underlying  Paint  Creek  and  Bethel  formations,  except  that 
in  some  parts  of  the  county  where  the  Bethel  is  well  exhibited,  the  higher 
sandstone  has  been  completely  removed  by  erosion.  In  the  southeastern 
portion  of  the  county  the  Cypress  occupies  a  belt  extending  from  the  Ohio 
River  bluffs  three  miles  east  of  Cave  in  Rock,  in  a  northwesterly  direction  to 


Miss.  Form.  West.   Ky.,  p.   64,    (1918). 

Trans.   St.  Uouis  Acad.   Sci.,  vol.   2,  pt.   1,  p.   189,    (1863), 


176  GEOLOGY  OF  HARDIN  COUNTY 

the  Peters  Creek  fault  limiting  the  central  faulted  zone.  The  maximum  width 
of  this  belt  is  about  one  mile,  but  in  places  it  is  but  a  small  fraction  of  a  mile. 

In  belt  number  three  of  the  faulted  zone  (see  figure  3),  in  the  line  of 
bluffs  extending  south  westward  from  a  little  northeast  of  Lead  Hill  to  Big 
Creek,  the  Cypress  has  been  eroded,  leaving  only  the  Bethel  as  the  bluff- 
forming  bed ;  but  in  both  belts  one  and  two  of  the  faulted  zone  the  Cypress  is 
present.  In  the  complexly  faulted  portion  of  belt  number  two  the  formation 
is  limited  in  its  surface  outcrop  to  the  southeastern  border,  and  is  well 
exposed  in  a  number  of  the  fault  blocks  from  a  point  southeast  of  the  Keelin 
School  to  Fair  view.  For  the  most  part  these  are  rather  elongate,  narrow 
areas,  although  two  of  the  smaller  fault  blocks  about  one  mile  north  of  the 
bridge  over  Big  Creek  near  Elizabethtown,  include  small  areas  of  Cypress. 
In  belt  one  of  the  faulted  zone  the  Cypress  occupies  a  narrow  strip  extending 
in  a  northeasterly  direction  from  Gross  to  the  valley  of  Goose  Creek,  with  only 
a  slight  interruption  at  one  point  by  faulting.  A  small  patch  of  the  sandstone 
is  also  present  at  the  point  of  a  wedge-shaped  fault  block  in  sec.  20,  T.  11  S., 
R.  9  E. 

In  the  northwestern  part  of  the  county,  the  Cypress  occupies  its  normal 
position  in  the  stratigraphic  succession,  the  outcrop  being  a  narrow  belt  in 
the  concentric  arrangement  of  the  formations  about  the  Hicks  dome,  extend- 
ing from  the  Pope  County  line  east  to  the  Lee  fault.  Beyond  this  fault  the 
formation  is  offset  to  the  south  for  about  one  mile,  whence  it  continues  to  the 
Wolrab  Mill  fault. 

LITHOLOGIC    CHARACTER 

The  Cypress  sandstone  is  a  massive  formation,  similar  in  many  respects 
to  the  Bethel  where  that  formation  exhibits  its  greatest  development.  Much 
of  it,  however,  especially  the  upper  portion,  is  more  evenly  bedded  than  the 
Bethel,  and  in  places  the  regular  bedding  in  some  exposures  has  much  the 
appearance  of  regular  courses  of  masonry.  The  sand  of  which  the  formation 
is  constituted  is  fine-grained,  and  in  the  fresher  exposures  is  light  yellow- 
brown  or  buff  colored,  or  in  places  almost  white.  The  weathered  surfaces  are 
commonly  darker  colored,  becoming  brownish  or  reddish-brown.  Locally  there 
are  numerous  ferruginous  streaks  and  bands  through  the  sandstone,  but  else- 
where it  is  free  from  such  markings. 


THICKNESS 


The  entire  thickness  of  the  Cypress  sandstone  is  not  commonly  exhibited 
in  Hardin  County,  and  no  locality  has  been  observed  where  the  underlying  and 
overlying  formations  are  exposed  in  one  continuous  section.  In  most  situa- 
tions the  Cypress  forms  an  abrupt  bluff  with  no  younger  formation  retained 
on  the  summit,  and  it  is  quite  likely  that  the  formation  in  such  exposures  has 


UPPER   MISSISSIPPI  AN    SERIES,    CHESTER   GROUP  177 

been  reduced  in  thickness  by  erosion.  One  of  the  best  bluff  sections  where 
the  Cypress  is  present  lying  upon  the  Paint  Creek  shale  is  at  Birds  Bluff  in 
Pope  County,  four  and  one-half  miles  below  Golconda.  In  this  section  70 
feet  of  Cypress  is  exposed,  and  although  the  section  is  in  Pope  County  it  is 
probably  representative  for  Hardin  County  as  well.  The  total  maximum 
thickness  may  of  course  have  been  somewhat  greater  than  70  feet,  due  to 
erosion  from  the  top  of  the  bluff,  but  the  erosion  probably  has  not  been  very 
great.  Butts  has  estimated  a  thickness  of  110  feet  for  the  Cypress  sandstone 
northeast  of  Cave  in  Rock,  and  about  80  feet  in  the  northwestern  part  of  the 
county.  It  is  probable  that  the  average  thickness  of  the  formation  in  Hardin 
County  is  between  80  and  100  feet. 

STRATIGRAPHIC    RELATIONS 

The  stratigraphic  relations  of  the   Cypress  sandstone  with  neither  the 

underlying  nor  overlying  formations  have  been  determined  from  observations 

upon  the  actual  contacts  of  the  beds,  because  these  contacts  are  generally,  if 

not  everywhere  in  the  region,  entirely  obscured  by  surficial  deposits.    The  only 

fact  that  seems  to  have  some  bearing  upon  the  question  is  that  the  Paint 

Creek  shales  may  be  wanting  in  the  section  in  the  eastern  part  of  the  county. 

If  the  absence  of  this  formation  is  due  to  its  removal  by  erosion  preceding  the 

period  of  deposition  of  the  Cypress  sandstone,  such  an  erosion  interval  would 

indicate  the  presence  of  an  unconformity  at  the  base  of  the  Cypress.     On  the 

other  hand  it  is  possible  that  the  Paint  Creek  was  never  deposited  in  the  area 

where  it  now  seems  to  be  wanting.    The  stratigraphic  relations  of  the  Cypress 

to  the  overlying  Golconda  limestone  have  nowhere  been  clearly  shown  in  out- 

j  crop  because  of  insufficient  exposures,  but  the  presence  of  somewhat  calcareous 

sandy  beds  with  imperfectly  preserved  fossils   near  the  horizon  of  contact 

between  these  two  formations,  suggests  that  there  is  a  gradual  transition  from 

l  the,  lower  formation  to   the  higher.      That  the   sand   depositing  conditions 

changed  gradually  at  this  time  to  the  lime  and  shale  depositing  conditions  of 

I  Golconda  time,  is  further  shown  by  the  recurrence  of  the  earlier  conditions 

;  exhibited  by  the  sandstone  beds  which  are  locally  present  in  the  lower  part  of 

i  the  Golconda.     The  best  exhibitions  of  the  gradation  from  the  Cypress  sand- 

!  stone  into  the  Golconda  formation  are  to  be  seen  in  Pope  County,  in  the 

\  neighborhood    of   Golconda,    but    the    same    conditions    undoubtedly   prevail 

j  throughout  Hardin  County. 

PALEONTOLOGY 

The  fossils  most  commonly  met  with  in  the  Cypress  sandstone  are  frag- 
ments of  plant  remains  which  are  mostly  imperfect  trunks  of  Lepidodendron. 
Aside  from  these  plant  remains,  imperfectly  preserved  specimens  of  inverte- 
—12    G 


178 


GEOLOGY  OF  HARDIN  COUNTY 


brates  are  present.  The  forms  most  commonly  met  with  are  bryozoan  frag- 
ments, among  others  the  axes  of  Archimedes.  These  are  perhaps  most  com- 
mon in  the  lowermost  beds  of  the  formation  which  may  originally  have  been 
somewhat  calcareous. 

CORRELATION 

The  only  question  in  correlation  which  need  be  discussed  in  the  con- 
sideration of  the  Cypress  sandstone  in  this  report,  is  in  connection  with  its 
equivalent  in  the  Chester  section  exposed  in  Eandolph  and  Monroe  counties. 
Because  of  the  absence  of  an  adequate  fauna  the  correlation  of  the  Cypress  in 
this  western  Illinois  section  must  rest  primarily  upon  the  correlation  of  the 
underlying  and  overlying  beds  which  are  characterized  by  prolific  faunas.  It 
has  already  been  shown  by  the  faunal  evidence  that  the  Paint  Creek  formation 
of  the  two  regions  in  question  is  a  continuous  formation.  The  Cypress  is  a 
conspicuous  sandstone  formation  succeeding  the  Paint  Creek  in  southeastern 
Illinois,  occupying  the  same  stratigraphic  position  as  the  much  less  con- 
spicuous sandstone  bed  of  the  Euma  formation  in  the  more  western  counties. 
If  the  faunal  evidence  sustains  the  correlation  of  the  limestone  formations 
immediately  overlying  the  sandstone  in  the  two  sections,  then  the  correlation 
of  the  Cypress  with  the  Euma  is  apparently  established,  and  the  name  Euma 
should  be  dropped.  A  discussion  of  the  faunal  basis  for  the  correlation  of  the 
Golconda  limestone  of  southeastern  Illinois  with  the  lower  Okaw  of  the  more 
western  region  will  be  left  for  consideration  under  discussion  of  the  Golconda 
formation,  but  it  may  be  here  stated  that  such  a  correlation  is  made,  and 
therefore  the  Cypress  and  Euma  sandstones  are  considered  to  be  equivalent 
formations. 

It  has  already  been  brought  out  that  the  Bethel  sandstone  of  Hardin 
County  and  the  surrounding  region  becomes  much  reduced  in  thickness  as  it 
extends  into  the  more  western  part  of  the  Illinois  Chester  basin.  The  same 
condition  is  exhibited  in  the  case  of  the  Cypress  sandstone,  the  formation 
being  80  or  more  feet  thick  in  Hardin  County,  while  in  Eandolph  it  is  reduced 
to  less  than  one-third  of  that  amount,  and  in  Perry  County,  Missouri,  it  is 
wanting  entirely. 

Golconda  Formation 


NAME    AND    DISTRIBUTION 

The  Golconda  formation  has  been  so  named  from  the  excellent  exposures 
of  the  formation  just  north  of  Golconda,  in  Pope  County,  in  the  bluffs  of  Lusk 
Creek  and  Ohio  Eiver.  The  formation  has  been  recognized  across  Hardin, 
Pope,  and  Johnson  counties,  Illinois,  and  when  detailed  work  is  done  it  will 
doubtless  be  found  to  extend  to  the  west  into  Union  County.  Throughout  the 
whole  of  this  region  the  formation  is  certainlv  known  to  be  present  wherever 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER   GROUP  179 

this  part  of  the  Chester  section  forms  the  surface  rocks,  and  it  is  also  charac- 
teristically developed  in  Crittenden  and  Livingston  counties,  Kentucky.  The 
complete  geographic  distribution  of  the  formation  can  only  be  determined 
when  more  detailed  mapping  has  been  done.  The  formation,  however,  is 
essentially  a  formation  of  the  Ohio  Valley  region  and  does  not  continue  as  a 
distinct  unit  into  the  Mississippi  Valley  Chester  region,  although  it  is  repre- 
sented in  the  Eandolph  and  Monroe  county  section  by  the  lower  division  of 
the  Okaw  limestone. 

In  Hardin  County  outcrops  of  the  Golconda  formation  occur  in  each  of 
the  three  regions  into  which  the  county  is  divided  structurally.  In  the  south- 
eastern region  the  formation  outcrops  in  the  point  of  the  river  bluff  about  four 
miles  northeast  of  Cave  in  Eock,  and  about  one  mile  from  Fraileys  Store. 
From  this  point  the  outcrop  continues  northwest  in  a  narrow  belt  to  its  inter- 
section with  the  northeast-southwest  faults  which  bound  the  central  faulted 
area. 

Within  the  central  faulted  region  of  the  county  (see  figure  3),  the  Gol- 
conda formation  is  exposed  in  a  number  of  different  blocks,  the  most  extensive 
exposures  being  present  southeast  of  the  deeply  downdropped  Pottsville  block, 
and  in  that  part  of  the  region  lying  southwest  of  Keelin  School.  A  small 
area  of  outcrop  is  present  just  south  of  the  middle  of  sec.  12,  T.  12  S.,  E.  8  E., 
and  another  better  exposed  though  smaller  outcrop  is  present  in  the  SE.  % 
sec.  11,  just  to  the  west.  The  largest  of  the  fault  blocks  exhibiting  the  Gol- 
conda formation  lies  mostly  in  sees,  15  and  16,  T.  12  S.,  E.  8  E.  A  large  hill 
which  constitutes  the  major  portion  of  this  fault  block  is  made  up  exclusively 
of  Golconda  limestone,  capped  by  Hardinsburg  sandstone  the  strata  being 
essentially  horizontal.  In  this  block  good  outcrops  of  the  formation  may  be 
seen  just  north  of  the  middle  of  sec.  15,  and  along  the  tributary  of  Big  Creek 
which  flows  southwest  from  the  northeast  corner  of  sec.  16.  Another  block 
within  this  faulted  zone  where  the  Golconda  limestone  forms  the  surface  rock 
over  a  considerable  area  but  is  poorly  exposed,  lies  west  of  Eosiclare.  This 
block  is  narrowly  elongate  in  outline,  its  northern  extremity  being  at  Stone 
Church.  The  Golconda  formation  is  present  at  the  surface  in  much  of  the 
southern  half  of  this  block,  the  greater  part  of  the  outcrop  being  in  sec.  32, 
T.  12  S.,  E.  8  E.,  but  extending  over  into  the  adjacent  sections  to  the  north, 
south,  and  west.  The  actual  exposures  in  the  block  are  poor,  being  heavily 
covered  with  surficial  material.  One  or  two  other  smaller  fault  blocks  in  the 
region  under  consideration  also  include  some  Golconda  limestone,  as  is  shown 
upon  the  map. 

Northwest  of  the  southern  part  of  the  central,  more  deeply  downdropped 
belt  of  the  central  faulted  zone,  the  Golconda  limestone  is  exposed  in  only  one 
small  fault  block  in  sec.  25,  T.  12  S.,  E.  7  E.,  along  a  hill  slope  to  the  east 
of  Wallace  Branch.     In  the  northern  part  of  belt  one  of  the  central  faulted 


180 


GEOLOGY  OF  HABDIN  COUNTY 


zone,  however,  the  Goleonda  occupies  its  normal  position  as  a  narrow  belt 
extending  in  a  northeast  direction  from  the  Wolrab  Mill  fault,  along  the 
northern  walls  of  Harris  Creek  and  Goose  Creek  valleys. 

In  the  northwestern  portion  of  the  county  the  Goleonda  is  present  as  a 
narrow  band,  occupying  its  normal  position  among  the  formations  arranged 
concentrically  about  the  Hicks  dome.  From  the  Pope-Hardin  county  line 
eastward  to  Karbers  Ridge,  the  formation  forms  the  northern  wall  of  the 
valley  of  Pinhook  Creek,  the  easily  decomposed  shale  and  the  thin  bedded 
limestone  of  the  formation  being  the  cause  of  the  location  of  the  valley  in 
its  present  position.  Eastward  from  Karbers  Ridge  the  Goleonda  formation 
again  outcrops  in  the  north  wall  of  a  valley  tributary  to  Big  Creek.  At  the 
Lee  fault  the  Goleonda,  like  the  other  formations,  is  offset  to  the  southwest, 
and  then  continues  eastwardly  to  the  Wolrab  Mill  fault,  again  forming  the 
north  wall  of  a  valley  tributary  to  Big  Creek.  The  location  of  these  valleys 
upon  the  outcrop  of  the  Goleonda  formation  is  an  excellent  example  of  the 
operation  of  a  general  law,  that  in  regions  of  tilted  rock  strata  of  alternate 
sandstone,  limestone  and  shale  beds,  the  valleys  are  invariably  worn  down  in 
the  limestone  and  shale  formations,  leaving  the  sandstone  areas  as  projecting 
ridges.  The  reason  for  this  is,  of  course,  that  the  shale  and  limestone  are 
softer  and  are  more  easily  worn  away  than  the  sandstone  or  highly  siliceous 
rocks,  which  are  harder  than  the  shales  and  less  soluble  than  the  limestones, 
and  therefore  more  resistant  to  the  processes  of  erosion. 


LITHOLOGIC   CHARACTER 

The  Goleonda  formation  is  essentially  a  succession  of  limestones  and 
shales,  but  the  outcrops  are  so  generally  talus  covered,  that  the  details  of  the 
successive  beds  are  obscured.  It  can  be  stated,  however,  that  a  considerable 
body  of  limestone  is  present,  locally  at  least,  in  the  basal  portion  of  the  forma- 
tion, followed  above  by  a  rather  thick  body  of  shale  with  intercalated  thin 
layers  of  limestone,  this  again  succeeded  by  another  limestone  member,  or  by 
two  limestone  members  separated  by  shale.  Besides  the  main  shale  members 
there  are  numerous,  thin,  shaly  partings  between  beds  of  limestone. 

The  individual  beds  o£  limestone  in  the  formation  vary  somewhat  in 
character,  but  in  the  main  they  are  gray  or  bluish  in  color,  and  more  or  less 
crystalline.  Some  minor  beds  are  dense  and  compact  in  texture,  but  such 
beds  are- not  conspicuous.  The  limestone  beds  in  the  lower  portion  of  the 
formation  are  a  mass  of  fossil  fragments  which  weather  with  a  rough  surface, 
and  in  the  weathered  outcrops,  at  least,  are  likely  to  be  stained  a  rusty  brown 
color,  either  more  or  less  uniformly  or  in  irregular  streaks.  Oolitic  beds  are- 
present,  but  except  locally  they  constitute  a  very  inconspicuous  portion  of  the 
formation  and  have  been  observed  at  but  a  single  locah*tv  in  Hardin  County. 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  181 

Chert  is  very  rare  in  the  formation,  and  none  whatever  has  been  observed 
in  any  Hardin  County  locality. 

The  shales  of  the  Golconda  formation  are  fully  as  variable  in  character 
as  the  limestones.  Some  beds  are  almost  wholly  argillaceous  and  gray,  bluish, 
or  essentially  black  in  color.  Other  beds  are  calcareous,  and  gradations  may 
be  observed  from  the  moderately  calcareous  shales  to  thinly  bedded  limestones 
with  a  considerable  content  of  argillaceous  material.  At  one  or  two  localities 
in  Pope  County  a  thin  bed  of  red  shale  has  been  met  with  in  the  Golconda 
formation,  and  while  no  such  bed  has  yet  been  observed  in  Hardin  County  its 
occurrence  would  not  be  unexpected.  In  the  lower  portion  of  the  formation 
some  of  the  shale  beds  are  more  or  less  sandy,  and  they  pass  locally  into  sand- 
stone beds  of  minor  importance. 

THICKNESS 

Because  of  the  lithologic  character  of  the  formation  the  outcrops  of  the 
Golconda  formation  are  commonly  heavily  covered  with  talus,  so  that  the 
actual  detailed  succession  of  beds  cannot  be  elaborated.  It  is  also  difficult  in 
many  places  to  determine  with  accuracy  the  thickness  of  the  formation.  Per- 
haps the  best  section  in  Hardin  County  for  such  a  determination  is  that 
exposed  in  the  NW.  %  NE.  %  sec.  16,  T.  12  S.,  E.  8  E.  At  this  point  there 
is  at  least  140  feet  of  the  limestone  and  shale,  but  neither  the  base  nor  the 
summit  of  the  formation  is  determined  by  the  underlying  and  overlying  form- 
ations. It  is  probable,  however,  that  the  exposure  constitutes  almost  the  whole 
of  the  formation.  In  Pope  County,  near  Golconda,  there  is  an  interval  of 
about  150  feet,  between  the  top  of  the  Cypress  sandstone  and  the  base  of  the 
Hardinsburg,  which  would  make  the  thickness  approximately  the  same  as 
that  observed  in  Hardin  County. 

STRATIGRAPHIC    RELATIONS 

Wherever  the  Golconda  formation  is  known  it  rests  upon  the  Cypress 
sandstone,  and  although  the  contact  between  the  two  formations  is  covered 
in  every  locality  examined,  it  is  altogether  probable  that  no  stratigraphic 
break  occurs  between  the  two  formations.  The  Cypress  sandstone  becomes 
somewhat  more  thinly  bedded  towards  the  summit,  and  in  the  lower  portion 
of  the  Golconda  there  are  arenaceous  shales  and  some  impure  sandstone  beds. 
The  lithologic  gradation  from  the  lower  formation  to  the  higher  is  probably 
complete. 

The  stratigraphic  relations  of  the  Golconda  formation  with  the  overlying 
Hardinsburg  sandstone  are  well  exhibited  in  Pope  County,  in  the  Ohio  Elver 
bluffs  above  Golconda,  and  also  in  Johnson  County,  but  are  not  so  well  shown 
in  Hardin  County.  At  the  locality  above  Golconda  where  the  contact  between 
the  two  formations  has  been  observed  the  line  is  sharply  defined,  the  change 


182  GEOLOGY   OF   HARDIN    COUNTY 

from  limestone  to  massive  sandstone  is  abrupt  without  the  slightest  inter- 
gradation,  the  upper  surface  of  the  limestone  is  uneven  and  rolling  in  char- 
acter, and  the  topmost  portion  of  the  limestone  is  oxidized  to  a  distinctly  red 
color.  A  similar  condition  is  exhibited  in  Johnson  County,  in  Bald  Knob, 
•i  miles  south  of  Vienna.  These  facts  point  to  a  stratigraphic  break  and  a 
plane  of  unconformity  between  the  two  formations.  In  Hardin  County,  on 
the  Shawneetown  road  north  of  Cave  in  Eock,  and  in  the  bluff  to  the  north 
of  Goose  Creek  in  Eock  Creek  Township,  the  Golconda  passes  into  the  Hardins 
burg  through  10  feet  or  more  of  very  thinly  laminated  sandstone,  a  condition 
that  is  not  so  distinctive  of  unconformable  relations. 

PALEONTOLOGY 

The  fauna  of  the  Golconda  formation  exhibits  certain  characteristics 
which  are  persistent  throughout  its  extent  from  Johnson  County,  Illinois,  to 
Crittenden  County,  Kentucky.  The  best  collections  of  fossils  have  not  been 
secured  in  Hardin  County,  so  that  collections  from  outside  of  the  county  will 
be  called  upon  to  some  extent  in  connection  with  the  discussion  of  the  fauna. 

One  of  the  best  collections  of  Golconda  fossils  from  Hardin  County  has 
been  secured  from  the  southeastern  part  of  the  county,  near  the  middle  of  the 
SE.  %  sec.  9,  T.  12  S.,  E.  10  E.,  about  three  and  three-fourths  miles  north- 
east of  Cave  in  Eock.  The  following  species  have  been  identified  in  this 
collection : 

Fossils  from  the  Golconda  formation  collected  in  the  SE.  1i  sec.  9,  T.  12  S.,  R.  10  E. 

Triplophyllum      spinulosum      (M.-E.         Orthotetes     kaskaskiensis      (McChes* 

and  H.)  ney) 

Pentremites  Platybasis  n;sp.  Productus  ovatus  Hall 

Pterotocrinus  capitalis  Lyon  Diaphragmus  elegans  (N.  and  P.) 

Eridopora  punctifera  Ulrich  Rhynchopora  perryensis  Weller 

Penestella   (several  species)  Dielasma  sp. 

Archimedes  communis  Ulrich  Girtyella  brevilobata   (Swallow) 

Archimedes  ccnfertus  Ulrich  Spiriferina  spinosa   (N.  and  P.) 

Archimedes  lativolvis  Ulrich  Spiriferina    transversa    (McChesney) 

Archimedes  swallovanus  Hall  Spirifer  leidyi  N.  and  P 

Archimedes  terebriformis  LTlrich  Martinia  sp. 

Polypora  spinulifera  Ulrich  Reticularia  setigeia    (Hall) 

Reteporina  flexuosa  (Ulrich)  Cliothyridina  sublamellosa  (Hall) 

Septopora  subquadrans  Ulrich  Composita  trinuclea    (Hall) 

Orbiculoidea  sp.  Phillipsia  sp. 

As  already  pointed  out  the  best  exposures  of  the  Golconda  formation  in 
the  central  faulted  zone  of  Hardin  County  are  in  the  comparatively  large 
fault  block  which  lies  mostly  in  sees.  15  and  16,  T.  12  S.,  E.  8  E.  Fossil  col- 
lections have  been  made  from  a  number  of  localities  within  this  fault  block, 
and  the  following  combined  list  is  a  record  of  all  the  species  which  have  been 
identified  from  these  localities: 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP 


183 


Fossils  from  the  Golconda  formation  collected  from  exposures  in  the  fault  block 
lying  in  sees.  15  and  10,  T.  12  8.,  R,  S  E. 


Triplophyllum      spinulosum      (M.-E. 

and  H.) 
Pentremites  platybasis  n.sp. 
Pentremites  lyoni  Ulrich 
Pentremites  sp. 
Pterotocrinus  capitalis  Lyon 
Cornulites  sp. 
Spirorbis  sp. 

Fistulipora  excelens  Ulrich 
Eridopora  punctifera  Ulrich 
Batostomella  ?  sp. 
Stenopcra  tuberculata  Prout. 
Fenestella  cestriensis  Ulrich 
Fenestella    (several  species) 
Archimedes  swallovanus  Hall 
Archimedes  terebriformis  Ulrich 
Polypora  sp. 

Septopora  subquadrans  Ulrich 
Orthotetes     kaskaskiensis     (McChes- 

ney) 


Productus  inflatus  McChesney 
Productus  ovatus  Hall 
Diaphragmus  elegans   (N.  and  P.) 
Pustula  sp. 

Camarophoria     explanata      (McChes- 
ney) 
Rhynchopora  perryensis  Weller 
Dielasma  sp. 

Girtyella  brevilobata   (Swallow) 
Spiriferina  spinosa  (N.  and  P.) 
Spiriferina  transversa    (McChesney) 
Spirifer  increbescens  Hall,  var. 
Spirifer  leidyi  N.  and  P. 
Reticularia  setigera  (Hall) 
Eumetria  vera   (Hall) 
Cliothyridina  sublamellosa   (Hall) 
Composita  trinuclea   (Hall) 
Orthonychia  chesterensis  M.  and  W. 
Nautilus  ?  sp. 
Phillipsia  sp. 


These  Hardin  County  lists  do  not  include  all  of  the  species  that  are 
known  from  the  Golconda  limestone.  Fossil  collections  from  Pope  and  John- 
son counties  and  from  Kentucky  contain  a  number  of  additional  species,  any 
one  of  which  may  be  looked  for  in  this  county.  Xevertheless  the  already 
known  Hardin  County  collections  include  most  of  the  characteristic  faunal 
elements  of  the  horizon.  Tin;  Go]conda  limestone  species  now  known  from 
outside  Hardin  County,  but  not  yet  observed  within  the  county,  so  far  as 
they  have  been  specifically  identified,  are  as  follows.  This  list,  however,  does 
not  include  a  number  of  species  that  have  been  collected  in  one  Johnson 
County  locality  where  an  unusual  Golconda  fauna  has  been  discovered.  This 
fauna  will  be  discussed  separately  because  of  its  important  bearing  on  the 
correlation  of  the  formation. 


Fossils  from  the  Golconda  formation  collected  at  miscellaneous  localities  outside  of 

Hardin  County 


Pentremites  obesus  Lyon 
Agassizocrinus  sp. 
Stenopcra  cestriensis  Ulrich 
Anisotrypa  solida  Ulrich 
Lioclema  ?  araneum  Ulrich 
Fenestella  elevatipora  Ulrich 
Fenestella  serratula  Ulrich 
Fenestella  tenax  Ulrich 
Archimedes  compactus  Ulrich 
Archimedes  proutanus  Ulrich 


Polypora  cestriensis  Ulrich 
Polypora  tuberculata  Prout 
Lyropora  quincuncialis  Ulrich 
Thamniscus  furcillatus  Ulrich 
Septopora  cestriensis  Ulrich 
Streblotrypa  nicklesi  Ulrich 
Crania  chesterensis  M.  and  G. 
Martinia  contracta  M.  and  W. 
Martinia  sulcata  Weller 
Euomphalus  planidcrsatus  M.  and  W. 


184  GEOLOGY  OF  HARDIN  COUNTY 

Besides  the  forms  here  listed  there  are  a  number  of  small  species  of 
molluscs,,  commonly  poorly  preserved,  that  have  not  been  specifically  de- 
termined, and  whose  genera,  also,  in  some  cases  are  uncertain. 

Most  of  the  species  in  these  lists  are  wide  ranging  Chester  forms  and 
would  not  be  out  of  place  in  any  Chester  fauna  from  the  Shetlerville  to  the 
summit  of  the  group,  but  there  are  a  few  forms  that  are  highly  characteristic, 
and  the  combination  of  species  as  a  whole  is  known  at  no  other  Chester 
horizon.  One  of  the  most  characteristic  members  of  the  fauna  is  Pterotocrinus 
capitals.  This  crinoid  is  characterized  by  five  massive,  subglobose,  "wing- 
plates"  upon  the  ventral  side,  quite  different  from  the  "wing-plates"  of  any 
other  member  of  the  genus.  No  complete  example  of  the  species  has  been 
collected,  but  such  a  one  has  been  illustrated  by  Lyon.  It  is  the  massive 
"wing-plates"  of  the  species  that  are  commonly  met  with  in  the  collections, 
and  in  places  they  occur  in  great  numbers.  The  basal  plates  are  less  fre- 
quently met  with.  This  species,  however,  has  not  been  observed  in  the  higher 
beds  of  the  Golconda  limestone,  and  it  is  most  abundant  in  the  basal  portion 
of  the  formation.  The  bases  of  the  peculiar  crinoid  genus  Agassizocrinus 
become  common  in  some  of  the  Golconda  formation  collections,  for  the  firsi 
time  in  any  of  the  Chester  faunas.  The  genus  was  present,  but  always  rare, 
in  the  Paint  Creek,  but  beginning  with  the  Golconda  it  is  a  common  Chester 
form.  Another  characteristic  member  of  the  fauna  is  the  gigantic  Pentre- 
mites  obesus,  but  it  is  much  more  limited  in  its  range  and  distribution  than 
the  plates  of  Pterotocrinus  capitalis.  It  has  only  been  found  in  the  lower 
portion  of  the  formation  and  as  yet  has  been  collected  from  but  few  localities, 
none  of  them  in  Hardin  County.  Another  pentremite  that  is  characteristic 
of  the  formation,  and  which  is  very  much  more  common  than  P.  ohesus  is 
P.  platybasis.  One  of  the  Golconda  species  which  is  introduced  for  the  first 
time  at  this  horizon  in  the  southeastern  Illinois  section,  is  Camarophoria  ex- 
planata,  which  is  present  in  nearly  every  collection  and  which  is  very  common 
or  abundant  in  many  localities.  Oliothyridma  sublamellosa  and  Composita 
trinuclea  which  were  conspicuous  species  in  the  lower  Chester  faunas,  continue 
as  common  members  of  the  Golconda  fauna,  but  their  association  with 
Camarophoria  expianata  in  this  horizon  is  very  different  from  their  earlier 
occurrence.  Another  important  species  in  the  Golconda  fauna,  one  that  has 
been  collected  in  widely  different  localities  from  Johnson  County,  Illinois,  to 
Crittenden  County,  Kentucky,  but  which  is  nowhere  a  common  form,  is 
Rhynchopora  perryensis.  Rhynchonelloid  shells  are  everywhere  unusual  in 
the  Chester  faunas  of  the  Illinois  basin,  and  this  species,  originally  described 
from  the  lower  Okaw  limestone  of  western  Illinois,  is  the  only  one  which  so 
far  has  been  recorded  from  the  region,  and  it  has  been  observed  at  no  other 
horizon  in  the  southeastern  Illinois  section.  The  bryozoans  of  the  fauna  are 
of  the  usual  Chester  forms,  and  most  of  them  have  a  long  geologic  range 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER    GROUP 


185 


within  the  group.  One  of  the  characteristic  features  exhibited  by  this  ele- 
ment of  the  fauna  is  the  abundance  of  axes  of  the  genus  Archimedes  belonging 
to  a  number  of  different  species.  Archimedes  swallovanus  is  the  commonest 
species.  A.  compactus  which  was  so  commonly  present  in  the  Paint  Creek 
faunas  is  rarely  met  with  here. 

A  very  unusual  Golconcla  fauna  has  been  collected  in  Johnson  County, 
in  the  NW.  %  SE.  %  sec.  22,  T.  13  S.,  R.  3  E.,  in  which  there  is  an  associa- 
tion of  species  that  has  not  been  met  with  elsewhere  in  southeastern  Illinois, 
but  which  is  present  in  the  lower  portion  of  the  Okaw  limestone  in  Randolph. 
County.  Because  of  the  important  bearing  that  this  collection  has  upon  the 
correlation  of  the  Golconda  formation,  it  may  be  discussed  in  this  place.  The 
species  present  in  the  fauna,  as  they  have  been  identified,  are  as  follows : 


Fossils  collected  from  the  Golconda  formation  in  the  NW.  %  SE.  y±  sec.  22,  T.  13  S., 
R.  3  E.,  Johnson  County,  Illinois 


Triplophyllum     spinulosum      (M. — E. 

and  H.) 
Pentremites  sp. 
Pterotocrinus  capitalis  Lyon 
Pterotocrinus  sp. 
Crinoid  plates 

Stenopora  tuberculata  Prout 
Fenestella   (several  species) 
Archimedes  sp. 
Polypora  sp. 
Coeloconus  sp. 

Bryozoans   (several  undet.  spec.) 
Orthotetes     kaskaskiensis      (McChes- 

ney) 
Productus  ovatus  Hall 
Diaphragmus  elegans  (N.  and  P.) 
Camarophoria     explanata      (McChes- 

ney) 
Dielasma  sp. 

Spiriferina  spinosa  (N.  and  P.) 
Spirifer  increbescens  var.  americana 

Swallow 
Spirifer  increbescens  var. 
Martinia  contracta   (M.  and  W.) 
Eumetria  vera   (H'all) 
Cliothyridina  sublamellosa    (Hall) 
Composita  trinuclea   (Hall) 
Sphenotus  sp. 
Nucula  randolphensis  n.sp. 


Nucula  platynotus  n.sp. 

Nucula  sp. 

Leda  sp. 

Parallelodon  sp. 

Conocardium  chesterensis  n.sp. 

Myalina  sp. 

Myalina  sp. 

Schizodus  depressus  Worthen 

Schizodus  sp. 

Schizodus  (?)    sp. 

Aviculopecten   (several  species) 

Lepetopsis  sp. 

Bellerophon  chesterensis  n.sp. 

Euphemus   randolphensis   n.sp. 

Bucanopsis  ornatus  n.sp. 

Ptychomphalus  pp. 

Ptychornphalus  sp. 

Mourlonia  sp. 

Holopea  sp. 

Orthoceras  cf 

Cycloceras  cf. 

Cycloceras  sp. 

Nautilus  sp. 

Discitoceras  sp. 

Stroboceras  sp. 

Phillipsia  sp. 

Phillipsia  sp. 

Cladodus  sp. 

Pish  teeth   (several  species) 


okawense  M.   and  W. 
sequoyahensis  Snider 


The  really  significant  members  of  this  fauna  are  found  among  the 
molluscs,  essentially  all  of  which  are  undescribed  species.  No  attempt  will 
be  made  in  this  place  to  describe  and  name  all  of  the  new  forms,  but  descrip- 


186  GEOLOGY   OF    HARDIN    COUNTY 

tions  of  a  few  of  the  more  abundant  and  characteristic  species  will  be  pre- J 
sented  in  the  paleontological  chapter  of  this  report.  A  fauna  similar  to  this 
one  occurs  in  a  number  of  localities  in  the  lower  part  of  the  Okaw  limestone 
of  Eandolph  County,  Illinois,  and  all  of  the  new  species  which  are  here  de-: 
scribed  as  well  as  most  of  the  other  new  forms,  are  recognized  in  both  Ean- 
dolph and  Johnson  counties.  In  the  Randolph  County  collections  no  examples 
of  Pterotocrinus  capitalis  have  been  observed,  but  here  in  the  Johnson  County 
collection  this  best  index  fossil  of  the  Golconda  is  found  associated  with 
species  peculiarly  characteristic  of  the  lower  portion  of  the  Lower  Okaw 
limestone. 

Correlation 

A  comparison  of  the  fauna  of  the  Golconda  formation  with  the  Chester 
faunas  that  have  been  studied  from  the  Mississippi  valley  counties  in  Illinois, 
establishes  a  very  close  relationship  between  the  Golconda  and  the  lower  por- 
tion of  the  Okaw  limestone.  Every  identified  species  in  the  Golconda  fauna 
except  Pterotocrinus  capitalis  and  Pentremites  obesus  has  been  collected  in 
the  Okaw,  and  although  these  two  forms  are  among  the  most  diagnostic  mem- 
bers of  the  fauna,  their  absence  from  the  Okaw,  in  view  of  other  close  rela- 
tionships, may  be  considered  as  of  geographic  significance  rather  than  of  time 
value.  Among  the  faunal  characteristics  that  are  common  to  the  Golconda 
and  the  lower  Okaw,  are  the  following :  ( 1 )  The  first  introduction  and  abund- 
ant occurrence  of  Camarophoria  expianata.  (2)  The  presence  of  Rhyncho* 
pora  perryensis  in  both  faunas,  and  the  entire  absence  of  the  species  from  any 
other  horizon  in  both  of  the  sections.  This  is  a  representative  of  a  very 
unusual  type  of  brachiopod  in  the  Chester  faunas  of  the  Illinois  basin.  (3) 
The  common  occurrence  of  a  large  group  of  unclescribed  molluscs  in  both 
formations  which  are  unknown  in  any  other  Chester  fauna.  (4)  The  great 
increase  of  the  genus  Archimedes  in  both  of  these  faunas,  A.  sivallovanus. 
being  very  abundant  in  both,  and  A.  lativoivis  being  restricted  to  them  so  far 
as  known.  (5)  In  both  formations  the  bases  of  the  crinoid  genus  Agassizo- 
crinus  become  abundant  for  the  first  time,  although  they  had  been  present 
rarely  in  the  next  older  Paint  Creek  fauna  in  both  regions.  (6)  The  com- 
mon presence  of  Pentremites  platybasis  in  both  faunas,  and  so  far  as  known 
the  restriction  of  the  species  to  these  faunas.  (7)  The  abundance  of  the 
"wing  plates"  of  Pterotocrinus  in  both  faunas. 

While  any  one  of  the  above  mentioned  common  characteristics  might 
not  be  sufficient  to  establish  the  correlation  of  the  Golconda  with  the  lower 
Okaw,  the  multiplication  of  evidence  makes  the  case  very  strong,  especially 
when  taken  in  connection  with  the  stratigraphic  succession  of  the  faunas  in 
the  two  Chester  sections.  The  only  really  adverse  evidence  in  the  case  is 
the   absence  of  the  two  very  characteristic   Golconda   species,  Pterotocrinus 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  187 

capitalis  and  Pentremites  obesm,  from  the  Okaw,  but  these  species  may  yet 
be  found  in  that  formation,  or  their  absence  from  the  faunas  of  the  western 
side  of  the  basin  at  that  time  may  have  been  due  to  local  environmental  con- 
ditions, just  as  we  recognize  similar  geographic  differences  in  faunas  at  the 
present  time. 

In  the  recent  volume  published  by  the  Kentucky  Geological  Survey, 
devoted  largely  to  the  discussion  of  the  Chester  formations  of  the  western 
portion  of  that  state,  by  Chas.  Butts  and  E.  0.  Ulrich,  Ulrich1  has  correlated 
the  Cypress  sandstone  of  southeastern  Illinois  and  Kentucky,  with  the  lower 
division  of  the  Okaw  of  the  Mississippi  Eiver  section,  the  Golconda  being 
given  no  equivalent  in  the  more  western  section.  The  reasons  for  such  a  cor- 
relation are  nowhere  made  clear,  but  the  correlation  of  the  Golconda  with 
the  Lower  Okaw  is  apparently  rejected  because  of  the  absence  of  Pterotocrinus 
capitalis  from  the  Okaw  fauna.  A  hypothetical  "secondary  embayment 
*  *  *  between  St.  Louis  and  Cairo7'  is  assumed  to  have  been  in  existence 
during  that  portion  of  Chester  time  in  which  the  limestones  of  the  Okaw 
formation  were  being  deposited  while  the  Cypress  sandstone  was  being  formed 
in  southeastern  Illinois.  In  the  writer's  opinion  there  is  no  basis  whatsoever 
for  assuming  such  a  differentiation  of  the  Chester  basin.  The  correlation 
of  the  Golconda  with  the  Lower  Okaw,  which  is  indicated  by  the  similarity 
of  the  usual  faunas  of  the  two  formations,  is  rendered  doubly  sure  by  the 
evidence  of  the  fauna  listed  from  Johnson  County  in  which  the  "wing  plates" 
of  Pterotocrinus  capitalis,  the  most  characteristic  Golconda  species,  are  asso- 
ciated with  a  number  of  very  peculiar  and  unusual  Chester  species  which 
are  known  elsewhere  only  in  the  lower  portion  of  the  Okaw  in  Eandolph 
County,  and  with  the  establishment  of  such  a  correlation  the  correlation  of 
the  Cypress  with  the  Lower  Okaw  is  rendered  untenable. 

Hardinsburg  Sandstone 

name  and  general  distribution 

The  name  of  this  formation  has  been  brought  into  southeastern  Illinois 
and  the  adjoining  portion  of  Kentucky  from  Breckenridge  County,  Kentucky, 
east  of  the  western  coal  fields  of  that  state.  In  that  portion  of  Kentucky 
there  is  an  important  sandstone  formation  called  by  Butts2  the  Hardinburg, 
which  separates  two  distinct  limestone  formations  that  are  the  equivalents 
of  the  upper  and  lower  members  of  the  Okaw  formation  in  Eandolph  County, 
Illinois.  In  Hardin  and  the  other  southeastern  counties  of  Illinois,  a  similar 
sandstone,  lying  above  the  Golconda  formation,  occupies  the  same  stratigraphic 
position,  and  the  same  ncme  is  applied  to  it.    The  formation  is  well  developed 

1  Ky.   Geol.   Surv.,   Miss.   Form.   West.   Ky.,  p.    50;   pi.   D,   opp.   p.    47;   also  pp.    112-113, 
(1918). 

2Ky.  Geol.  Surv.,  Miss.  Form.  West.  Ky.,  p.  96    (1918). 


188  GEOLOGY  OP  HARDIN  COUNTY 

in  Kentucky,  both  east  and  west  of  the  coal  fields,  and  extends  westward  into 
Illinois  across  Hardin,  Pope,  and  Johnson  counties.  In  Eandolph  County 
the  formation  has  not  heretofore  been  differentiated,  but  there  is  locally 
present  between  the  lower  and  upper  divisions  of  the  Okaw,  a  sandstone  mem- 
ber which  is  doubtless  a  westward,  much  attenuated  extension  of  the  Hardins- 
burg  sandstone.  In  its  thinning  to  the  west,  the  Hardinsburg  sandstone 
resembles  both  the  Cypress  and  the  Bethel. 

In  the  southeastern  portion  of  Hardin  County  the  outcrop  of  Har- 
dinsburg sandstone  occupies  a  belt  extending  in  a  northwesterly  direction 
from  the  Ohio  Eiver  bluffs  just  below  where  Honey  Creek  enters  the 
bottom  land,  parallel  with  the  outcrop  of  the  earlier  Chester  formations,  to 
the  southeastern  border  of  the  central  faulted  zone,  the  width  of  the  outcrop 
being  approximately  one  mile.  At  the  southeastern  extremity  of  this  belt 
of  outcrop,  in  the  ravine  running  southeast  from  McDowell  School,  the 
formation  is  especially  massive  and  forms  prominent  bluffs  along  the  sides 
of  the  valley. 

In  the  central  faulted  zone  (see  figure  3)  the  Hardinsburg  sandstone 
outcrops  in  a  number  of  fault  blocks  in  association  with  the  underlying  Gol- 
conda  formation.  All  of  these  outcrops  lie  in  belts  one  and  two.  In  one  of 
the  elongate,  narrow  blocks  of  belt  two,  the  formation  is  exposed  in  a  north- 
easterly direction  from  near  the  center  of  sec.  12,  T.  12  S.,  R.  8E.  A  small 
area  is  underlain  by  the  formation  in  the  NW.  1/4  SW.  %  of  the  same  sec- 
tion, and  continues  westward  into  the  adjoining  section  11.  One  of  the 
largest  areas  of  outcrop  of  the  sandstone  is  in  the  fault  block  lying  mostly 
in' sees.  15  and  16,  T.  12  S.,  E.  8-  E.,  where  it  caps  the  hills  whose  lower 
slopes  are  underlain  by  the  Golconda  formation.  The  sandstone  exposed  in 
the  public  highway  about  three-fourths  of  a  mile  north  of  the  Eosiclare 
mine  at  Eosiclare,  is  Hardinsburg,  and  the  same  formation  caps  the  elongate 
hill  to  the  southwest,  whose  summit  is  nearly  opposite  the  Blue  Diggings 
shaft. 

In  the  southwestern  part  of  belt  number  one  of  the  faulted  zone,  the 
Hardinsburg  sandstone  is  exposed  in  only  one  small  area,  east  of  Wallace 
Branch,  in  sec.  25,  T.  12  S.,  E.  7  E.,  where  it  caps  an  enlongate  hill  whose 
lower  slope  is  occupied  by  the  Golconda  formation.  In  the  northern  portion 
of  this  belt  the  formation  outcrops  in  the  upper  part  of  the  hill  north  of 
Harris  Creek,  across  sec.  24,  T.  11  S.,  E,  8  E.,  and  after  crossing  this  creek 
the  outcrop  continues  in  a  northeasterly  direction  for  two  and  one-half  miles 
to  the  southeastern  border  of  the  belt. 

In  the  northwestern  third  of  the  county,  the  Hardinsburg  sandstone  out- 
crops continuously  on  the  upper  face  and  brow  of  the  bluff  on  the  north 
side  of  Pinhook  Creek,  and  continues  to  the  west  into  Pope  County  where 
it  forms  the  summit  of  the  west  bluff  of  Grand  Pierre  Creek.     It  is  the  first 


UPPER   MISSISSIPPI^    SERIES,    CHESTER   GROUP  189 

sandstone  met  with  on  ascending  the  bluff  north  and  west  of  these  streams, 
and  the  east-west  road  through  Karbers  Eidge  is  on  the  outcrop  of  this 
sandstone  from  one-third  of  a  mile  northwest  of  Philadelphia  School,  west- 
ward to  the  road  intersection  in  the  SE.  14  sec.  11,  T.  11  S.,  E.  7  E.  To 
the  east  the  outcrop  is  offset  to  the  southwest  by  the  Lee  fault.  Between  this 
fault  and  the  Wolrab  Mill  fault  the  formation  occupies  a  narrow  belt  in  its 
normal  position  in  the  Chester  group,  and  is  followed  by  the  ridge  road  to 
the  center  of  sec.  14,  T.  11  S.,  K.  8  E. 

LITHOLOGIC    CHARACTERS 

The  Hardinsburg  is  a  massive,  irregularly  cross-bedded  sandstone,  exhibit- 
ing much  evidence  of  its  shallow  water  origin  in  the  ripple-marks  and  other 
surface  markings  of  the  layers.  It  is  moderately  fine  grained,  and  in  color 
is  yellowish-brown,  the  weatherbeaten  surfaces  being  gray  or  reddish-brown. 
The  lower  portion  of  the  formation  is  more  massive  and  in  many  places 
rises  in  nearly  vertical  bluffs  above  the  underlying,  %talus-covered  slopes  of  the 
Golconda  formation.  The  higher  portion  of  the  formation  is  not  commonly 
so  well  exposed  as  the  lower,  and  is  apparently  less  massive,  more  thinly 
bedded,  and  locally  at  least,  there  are  minor  beds  of  shale.  Such  a  bed  of 
black  shale  included  in  the  Hardinsburg,  is  exposed  along  the  road  between 
Sparks  Hill  and  Karbers  Eidge,  in  the  ravine  crossing  the  middle  of  the 
east  half  of  sec.  10,  T.  11  S.,  E.  8  E.  The  bed  is  only  a  few  feet  in  thick- 
ness, and  should  possibly  be  assigned  to  the  next  overlying  formation,  the 
Glen  Dean  limestone.  In  general  the  formation  is  less  massive  than  the 
Cypress  sandstone,  but  locally  there  is  little  difference  in  this  respect  between 
the  two  formations.  On  Pinhook  Creek,  west  of  Karbers  Eidge,  the  forma- 
tion includes  a  considerable  thickness  of  evenly  bedded,  smooth  surfaced 
flagstones  that  have  been  quarried  on  a  small  scale  in  the  NW.  1/4  sec.  7, 
T.  11  S.,  E.  8  E. 

THICKNESS 

The  Hardin  County  outcrops  of  the  Hardinsburg  sandstone  are  not  gen- 
erally so  well  adapted  for  determining  the  thickness  of  the  formation  as  are 
some  of  those  in  Pope  County.  At  a  number  of  localities  in  that  county 
where  essentially  the  entire  thickness  of  the  formation  is  exposed,  there  are 
approximately  100  feet  of  the  sandstone.  At  some  localities  it  seems  to 
exceed-  this  thickness  somewhat,  and  elsewhere  it  is  considerably  less,  some 
sections  exhibiting  not  over  30  feet  as  on  the  ridge  between  Goose  and  Harris 
Creeks  in  Eock  Creek  Township.  In  one  deep  well  section  in  northern 
Pope  County,  80  feet  of  Hardinsburg  seems  to  be  present.  The  thickness  of 
the  formation  in  Hardin  County  is  doubtless  essentially  the  -same  as  in  Pope, 
and  an  average  thickness  of  from  75  to  100  feet  may  be  assumed. 


190  GEOLOGY    OF    HARDIN    COUNTY 

STRATIGRAPHIC    RELATIONS 

The  stratigraphic  relations  of  the  Hardinsburg  sandstone  with  the  under- 
lying Golconda  formation  have  already  been  considered,  and  the  evidence 
for  the  existence  of  a  plane  of  unconformity  between  the  two  formations,  as 
exhibited  in  Pope  County,  has  been  presented.  The  stratigraphic  relations 
between  the  Hardinsburg  and  the  overlying  Glen  Dean  limestone  are  nowhere 
so  clearly  shown  as  is  the  basal  contact  of  the  sandstone.  Wherever  the  sec- 
tion has  been  examined  the  interval  between  the  sandstone  and  the  overlying 
limestone  has  been  covered,  and  no  actual  contact  has  been  observed.  It  is 
a  fact,  however,  that  the  upper  portion  of  the  Hardinsburg  become  shaly, 
and  there  is  apparently  a  somewhat  gradual  transition  in  character  from  the 
lower  to  the  higher  formation  which  would  mean  continuity  of  sedimentation 
and  absence  of  any  relation  of  unconformity.  On  the  other  hand,  the  vary- 
ing thickness  of  the  Hardinsburg  sandstone  might  be  interpreted  as  evidence 
of  a  period  erosion  subsequent  to  its  deposition  and  before  the  deposition  of 
the  Glen  Dean  limestone. 

PALEONTOLOGY 

No  fossil  invertebrates  have  been  collected  in  the  Hardinsburg  sandstone, 
and  only  indeterminable  plant  fragments  have  been  observed  in  Hardin 
County  in  any  sandstone  or  shale  that  is  certainly  Hardinsburg  in  age.  In 
Pope  County  a  shale  bed  near  the  summit  of  the  formation  has  afforded  plant 
Temains  which  are  somewhat  better  preserved,  but  they  have  not  been 
critically  studied  by  a  paleobotanist ;  similar  material  may  be  looked  for  in 
Hardin  County. 

CORRELATION 

In  the  western  counties  of  Illinois  the  Okaw  limestone  is  a  thick  for- 
mation and  is  quite  clearly  not  a  simple  stratigraphic  unit.  It  has  been 
shown  that  the  lower  Okaw  is  the  time  equivalent  of  the  Golconda  formation, 
and  it  will  be  shown  later  that  the  upper  Okaw  is  to  be  correlated  with  the 
Glen  Dean  limestone;  but  in  Randolph  and  the  adjoining  counties  there 
is  no  thick  sandstone  formation  comparable  with  the  Hardinsburg,  separating 
the  two  parts  of  the  Okaw.  In  that  region  the  exposures  are  all  more  or  less 
drift  covered  in  most  places,  but  it  is  clear  that  locally  there  is  a  thin  sand- 
stone member  at  the  horizon  corresponding  to  the  dividing  line  between  the 
lower  and  upper  Okaw.  Elsewhere  it  is  certain  that  no  such  sandstone  bed 
separating  the  two  Okaw  members  is  present.  However,  all  the  evidence 
points  to  the  fact  that  this  thin  discontinuous  sandstone  horizon  in  Randolph 
County  is  the  much  reduced  equivalent  of  the  Hardinsburg  sandstone  of  the 
southeastern  part  of  the  state.  We  have  then,  in  the  Hardinsburg,  another 
example  of  a  thick  sandstone  formation  in  the  southeastern  part  of  the 
state,  like  the  Cypress  and  the  Bethel,  thinning  out  markedly  to  the  west. 


upper  mississippi  ax  series,  chester  group  191 

Glex  Deax  Limestone 
xame  and  distribution 

As  with  the  Hardinsburg  sandstone,  the  name  of  the  Glen  Dean  lime- 
stone is  brought  into  southeastern  Illinois  from  Breckenridge  County,  Ken- 
tucky, where  the  formation  has  been  named  by  Butts.1  In  a  "Preliminary 
Oil  Keport  on  Southern  Illinois"  by  A.  D.  Brokaw2,  and  later  in  the  final 
report  by  the  same  author3  and  in  a  report  by  Stuart  St.  Clair4,  this  limestone 
was  designated  as  the  Sloans  Valley  formation,  from  a  locality  in  Pulaski 
County,  Kentucky,  a  name  which  had  been  previously  used  as  a  field  desig- 
nation, but  which  had  not  been  published.  Butts  used  the  name  Glen  Dean 
for  the  formation  in  Breckenridge  County,  and  it  was  so  designated  by  Miller 
in  a  "Table  of  Geological  Formations  for  Kentucky,"  published  in  March, 
191 7.  Of  the  two  names  Glen  Dean  is  preferable.  The  Sloans  Valley  section 
is  less  well  known  than  that  of  southeastern  Illinois  and  the  adjacent  portions 
of  Kentucky,  and  it  is  not  unlikely  that  the  section  includes  much  more  than 
the  exact  equivalent  of  the  strata  for  which  the  name  has  been  used  in  Illinois. 
The  Glen  Dean  locality,  on  the  other  hand,  has  been  definitely  selected  by 
Butts  as  representing  the  formation  under  discussion,  limited  below  by  the 
Hardinsburg  and  above  by  the  Tar  Springs  sandstone. 

The  general  distribution  of  the  Glen  Dean  limestone  is  coextensive  with 
the  Hardinsburg  sandstone,  both  east  and  west  of  the  western  Kentucky  coal 
fields,  and  in  southern  Illinois,  where  it  extends  westward  through  Hardin, 
Pope,  Johnson,  and  Union  counties.  The  formation  has  its  equivalent  in 
Randolph  County  in  the  upper  division  of  the  Okaw  limestone. 

In  the  southeastern  portion  of  Hardin  County  the  Glen  Dean  limestone 
is  well  exposed  in  the  Ohio  River  bluff  at  and  just  west  of  the  point  where 
Honey  Creek  enters  the  river  bottoms,  a  little  less  than  one-half  mile  south- 
west of  Fraileys  Store.  From  this  point  the  formation  extends  northwestward 
in  a  narrow  belt,  to  the  southeastern  border  of  the  central  faulted  zone  of 
the  county.  The  upper  limestone  of  the  formation  is  well  exposed  at  a  num- 
ber of  points  in  Rock  Creek  and  Battery  Rock  townships.  One  such  exposure 
is  on  the  slope  on  the  southeast  side  of  the  ravine  crossing  the  southeastern 
part  of  sec.  32,  T.  11  S.,  R.  10  E.,  in  a  northeast-southwest  direction ;  another 
such  exposure  is  on  the  south  side  of  the  ridge  ending  eastwardly  in  the  SW. 
14  sec.  33,  T.  11  S.,  R.  10  E.,  where  35  feet  of  limestone  is  exposed  just 
beneath  the  Tar  Springs  sandstone  which  caps  the  ridge  and  the  low  knob 
to  the  east ;  still  another  outcrop  of  this  limestone  is  exposed  on  the  southeast 
angle  of  the  middle  of  the  three  spurs  in  the  northeast  corner  of  sec.  4,  T.  12 
S.,  R.  10  E.,  where  forty  feet  of  crinoidal  limestone  is  exposed,  mostly  gray 

1  Ky.  Geol.   Surv..  Miss.  Form.  West.  Ky..  n.  97    ("1918). 

2  111.  State  Geol.  Surv.,  Extr.  from  Bull.   35.  pi.  Ill    (1916). 

3  111.  State  Geol.  Surv.,  Bull.  35,  pi.  I   (1917). 

4  111.  State  Geol.  Surv.,  Bull.  35.  p.  46,  pi.  IV  (1917). 


192  GEOLOGY  OF  HARDIN  COUNTY 

in  color  but  somewhat  reddish  at  the  top.  A  very  good  exposure  of  the  Glen 
Dean  limestone  is  exhibited  in  the  southeastern  face  of  the  Ohio  River  bluff, 
above  the  road,  about  one-half  mile  southwest  of  Fraileys  Store.  The  outcrop 
of  the  Glen  Dean  limestone  in  the  ridge  between  Sheridans  Branch  and 
Little  Creek  on  the  southwest,  and  Honey  Creek  and  the  southeast  branch  of 
Bock  Creek  on  the  northeast,  is  conspicuously  marked  by  low  ground  and 
saddles  at  several  places.  One  of  the  best  examples  of  this  topographic  rela- 
tion is  in  the  north  part  of  sec.  26,  T.  11  S.,  E.  9  E.,  where  the  three  promi- 
nent knobs  are  capped  by  Tar  Springs  sandstone,  the  south  slopes  of  the  knobs 
and  the  low  saddles  just  to  the  south  are  occupied  by  the  Glen  Dean,  while 
the  long  slope  rising  somewhat  gently,  still  to  the  south,  is  occupied  by  the 
Hardinsburg  sandstone  dipping  beneath  the  Glen  Dean.  The  same  relation 
is  also  well  shown  in  the  west  side  of  the  NE.  y±  sec.  4,  T.  12  S.,  B.  10  E., 
where  the  Tar  Springs  also  caps  the  knobs  and  the  Glen  Dean  outcrops  on 
the  west  slopes  and  in  the  saddles. 

Within  the  central  faulted  zone  the  Glen  Dean  does  not  outcrop  in  belt 
number  three  (see  figure  3),  and  is  exposed  in  only  a  few  of  the  fault  blocks 
of  belt  number  two.  The  southernmost  of  these  areas  is  just  south  of  Stone 
School.  The  formation  is  poorly  exposed  at  this  place,  the  only  outcrops 
being  shale  and  of  very  small  extent.  Much  better  exposures  of  the  formation 
may  be  seen  a  little  less  than  one  mile  north  of  the  iron  bridge  over  Big  Creek 
on  the  Elizabethtown  and  Eosiclare  road,  the  exposures  being  upon  the  west 
side  of  a  valley  tributary  to  Big  Creek,  near  its  confluence  with  the  main 
creek.  This  outcrop  is  in  a  comparatively  small  fault  block  and  consequently 
does  not  have  any  great  lateral  extent.  Farther  to  the  northeast  the  Glen 
Dean  limestone  outcrops  in  the  elongate  fault  block  lying  northwest  of  Peters 
Creek,  as  a  narrow  belt  starting  in  the  KE.  l/4  sec.  12,  T.  12  S.,  E.  8  E,, 
and  continuing  four  miles  to  the  center  of  sec.  33,  T.  11  S.,  B.  9  E. 

In  belt  number  one  of  the  faulted  zone,  the  Glen  Dean  limestone  is  ex- 
posed only  towards  the  northern  part  of  the  county,  southeast  of  Sparks  Hill. 
The  upper,  massive  limestone  is  well  exposed  on  the  south  bluff  of  the  ridge 
north  of  Goose  Creek,  near  its  eastern  end  in  sec.  16,  T.  11  S.,  E.  9  E.  West 
from  this  locality  the  exposures  of  the  formation  are  poor,  being  largely 
covered.  The  position  of  the  limestone  is  in  a  narrow  belt  just  to  the  north- 
west of  the  outcrop  of  the  Hardinsburg  sandstone,  which  "has  been  described. 

In  the  northwestern  part  of  the  county  the  Glen  Dean  exposures  continue ' 
to  be  poor.  Between  the  Wolrab  Mill  and  Lee  faults  the  formation  extends 
in  a  narrow  belt  with  a  general  east-west  direction  nearly ' through  the  centers 
of  sees.  14  and  15,  T.  11  S.,  E.  8  E.  The  formation  occupies  a  depression 
between  the,  two  series  of  knobs,  those  to  the  south  being  capped  by  the 
Hardinsburg  and  those  to  the  north  by  the  Tar  Springs  sandstone.  West  of 
the  Lee  fault  the  Glen  Dean  is  offset  about  one  and  three-fourths  miles  to  the 


UPPER   MISSISSIPPIAN    SERIES,    CPIESTER    GROUP  193 

northeast,  that  is,  to  a  point  about  one-third  of  a  mile  north  of  Philadelphia 
School,  from  which  point  the  formation  continues  westward  in  a  narrow  belt 
to  the  Hardin-Pope  County  line.  Along  this  belt  the  limestone  is  exposed 
in  the  bottom  of  the  ravine  about  three-fourths  of  a  mile  north-northeast  of 
Karbers  Eidge,  in  the  center  of  the  NE.  %  sec.  9,  T.  11  S.,  E.  8  E.  In  the 
bead  of  the  ravine  in  the  NE.  y±  sec-  1^,  T.  11  S.,  E.  7  E.,  there  is  an  exposure 
of  the  limestone  which  is  crowded  with  one  of  the  most  distinctive  fossils  of 
the  formation,  the  bryozoan  Prismopora  serrulata,  and  another  characteristic 
fossil  occurring  at  the  same  locality  is  Pentremites  spicatus.  Massive  lime- 
stone beds  of  the  Glen  Dean  are  exposed  in  the  bed  of  Eose  Creek  in  the  NE. 
y±  SW.  %  sec.  11,  T.  11  S.,  B.  7  E.,  and  also  near  the  head  of  a  shallow  ravine 
in  the  SE.  14  SW.  l/^  of  the  same  section. 

Lithologic  Characters 

In  Hardin  and  the  adjoining  counties  in  Illinois,  the  Glen  Dean  forma- 
tion is  rather  obscure  because  its  lithologic  characters  are  such  as  to  render 
it  liable  to  be  hidden  by  surficial  covering.  In  favorably  situated  localities, 
however,  many  outcrops  of  the  formation  do  occur,  and  in  some  other  locali- 
ties its  presence  is  indicated  by  a  series  of  sink-holes  in  which  there  may  be 
no  actual  outcrops  of  the  limestone.  Like  the  Golconda  formation,  the  Glen 
Dean  consists  of  interbedded  limestones  and  shales.  The  limestone  beds, 
as  observed  in  different  localities,  exhibit  a  great  variety  of  lithologic  char- 
acters, the  different  beds  being  less  uniform,  even,  than  those  of  the  Golconda. 
In  general  the  limestone  of  the  Glen  Dean  formation  is  crystalline  and  gray 
or  nearly  black  in  color;  but  it  includes  beds  of  very  dense,  compact  and 
brittle  rock,  breaking  with  a  splintery  fracture,  these  dense  beds  commonly 
being  quite  dark,  in  fact  nearly  black  in  color.  The  crystalline  character  of 
the  limestones  is  due  to  the  presence  of  an  abundance  of  fossil  fragments, 
especially  crinoidal  plates,  and  on  extreme  weathering  the  beds  become  crumbly 
and  shaly.  In  a  few  localities  certain  calcareous  beds  of  the  formation  occur 
as  very  hard,  brittle  shales  or  shaly  limestone.  Some  of  the  beds  apparently 
are  very  pure,  while  others  are  highly  siliceous.  These  limestones  contain 
some  chert,  although  the  chert  is  much  less  conspicuous  than  in  the  higher 
limestones  of  the  Chester  group.  The  chert  commonly  occurs  in  plate-like 
layers  one  or  two  inches  thick,  most  or  all  of  which  are  colored  dark  chocolate- 
brown  on  freshly  broken  surfaces.  On  the  weathering  of  the  limestone  these 
cherts  break  into  subcubical  fragments  of  the  thickness  of  the  plates,  and 
remain  in  the  residuum.  Two  surfaces  of  the  subcubical  fragments,  those  in 
contact  with  the  inclosing  limestones  before  weathering,  are  commonly  decom- 
posed to  a  depth  of  about  one-half  inch,  becoming  porous  and  developing  a 

—13  G 


194 


GEOLOGY    OF    JIA1JDIN    COUNTY 


yellowish-brown  color.  In  some  localities  the  presence  of  these  chert  frag- 
ments in  the  residuum  is  the  only  evidence  of  the  existence  of  the  limestone. 

The  shales  of  the  Glen  Dean  also  lack  uniformity  in  character.  Some 
beds  are  argillaceous  and  break  down  into  a  plastic  clay,  other  beds  are  cal- 
careous, and  still  others  are  siliceous.  Between  some  of  the  denser  limestone 
layers  there  are  thin  shale  partings. 

While  the  composition  of  the  Glean  Dean  formation  in  the  western  part 
of  the  county  is  not  well  known,  owing  to  the  poor  exposures,  the  formation 
is  better  known  to  the  east  where  exposures  are  rather  better.  In  Bock  Creek 
and  Battery  Bock  townships  a  number  of  fairly  good  exposures  reveal  that  the 
upper  forty  feet  of  the  formation  is  a  coarsely  crystalline  crinoidal  limestone, 
and  that  the  lower  thirty  feet  or  so  includes  both  shales  and  limestones.  A 
nearly  complete  section  is  exposed  in  the  highway  in  the  northwest  corner 
of  sec.  15,  T.  11  S.,  B.  9  E.,  where  the  following  beds  may  be  seen: 

Section  of  the  Glen  Dean  limestone  in  the  northwest  corner  of  sec.  15,  T.  11  S„ 

R.  9  E. 

Fe< 

4.     Sandstone,  basal  portion  of  the  Tar  Springs 

3.     Limestone,  coarsely  crinoidal,  weathering  shaly  and  crumbly 40 

2.     Limestone  and  shale  interbedded 20 

1.     Limestone,  with  Lyropora,  Prismopora,  and  Pentremites  pyramiclatus 10 

The  upper  part  of  this  section  is  representative  for  the  region,  as  show] 
by  a  number  of  exposures  at  points  described  under  the  head  of  distribution. 
In  some  places  in  this  northeastern  part  of  the  county  a  few  feet  of  shale  is 
present  between  the  Glen  Dean  limestone  and  the  Tar  Springs  sandstone,  as 
for  example  in  the  road  on  the  south  face  of  the  low  bluff  in  the  center  ol 
sec.  33,  T.  11  S.,  B.  10  E. 

Another  feature  of  the  Glen  Dean  limestone  that  is  worthy  of  mentioi 
is  a  somewhat  widely  distributed  oolitic  limestone  bed  in  the  upper  part  oi 
the  formation.  This  bed  has  been  observed  most  commonly  in  the  southen 
part  of  Bock  Creek  Township  and  is  well  exposed  on  the  south  side  of  th( 
knob  at  the  head  of  Peters  Creek,  just  west  of  the  center  of  sec.  33,  T.  11  S. 
E,  9  E. ;  also  at  the  Martin  prospect  in  the  SW.  %  sec.  23,  T.  11  S.,  B.  9  E, 
and  on  the  south-facing  steep  slope  in  the  middle  of  the  east  side  of  sec.  21 
T.  11  S.,  B.  9  E.,  east  of  Douglas  School. 

THICKNESS 

The  outcrops  of  the  Glen  Dean  limestone  in  Hardin  County  do  not  afforc 
so  good  an  opportunity  for  determining  the  thickness  as  do  some  of  those  h 
Pope  County.  The  accurate  determination  of  the  thickness  of  the  formatioi 
is  difficult  throughout  the  area  because  of  the  nonresistant  shale  beds  in  th( 
formation  and  the  massive  sandstone  which  overlies  it,  a  set  of  condition? 
which  make  it  liable  to  be  more  or  less  completely  obscured  by  the  talus  froi 


UPPER   MISSISSIPP1AN    SERIES,    CHESTER   GROUP  195 

the  sandstone.  The  best  estimates  of  thickness  that  can  be  made  range  from 
50  to  70  feet,  and  about  60  feet  may  be  considered  a  fair  estimate  of  its 
thickness  in  Hardin  County.  In  general  it  may  be  said  that  the  Glen 
Dean  is  one  of  the  thinner  of  the  Chester  limestone  formations  in  the  south- 
eastern part  of  Illinois. 

STRATIGRAPHIO   RELATIONS 

The  outcrops  of  the  Glen  Dean  limestone  are  so  commonly  obscured  by 
talus  that  the  actual  contacts  with  the  subjacent  and  superjacent  formations 
have  nowhere  been  observed.  It  is  altogether  probable,  however,  that  the 
formation  rests  conformably  upon  the  underlying  Hardinsburg  sandstone.  As 
already  pointed  out  there  seems  to  be  a  gradation  from  the  Hardinsburg 
sandstone  through  a  shale  interval  into  the  typical  limestone  and  shale  of  the 
Glen  Dean  formation. 

There  is  perhaps  less  basis  for  certainly  determining  the  relations  between 
the  Glen  Dean  and  the  overlying  Tar  Springs  sandstone,  but  so  far  as  can 
be  determined  the  massive  sandstones  of  the  higher  formation  seem  to  succeed 
the  limestones  abruptly,  and  it  is  not  unlikely  that  the  younger  formation 
rests  unconformably  upon  the  older,  this  condition  being  essentially  the  same 
as  between  the  Hardinsburg  and  the  Golconda. 

PALEONTOLOGY 

The  unsatisfactory  exposure  of  the  Glen  Dean  limestone  in  Hardin 
County  accounts  for  the  somewhat  meager  fossil  collections  which  it  has 
afforded.  A  number  of  small  collections  have  been  secured,  however,  from. 
Hardin  and  the  adjoining  Pope  County  area  which  together  give  a  good  idea 
of  the  fauna.  The  best  collection  from  Hardin  County  has  been  secured  from 
the  locality  already  mentioned,  situated  a  little  less  than  one  mile  north  of 
the  iron  bridge  over  Big  Creek.  From  this  locality  the  following  species  have 
been  identified: 

Fossils  from   the   Glen   Dean   limestone  collected  in   the  WW.   y±   WE.   %   sec.   21, 

T.  12  8.,  R.  8  E. 

Triplophyllum      spinulosum      (M.-E.  Prismopora  serrulata  Ulrich 

and  H.)  Productus  inflatus  McChesney  ? 

Pentremites  brevis  Ulrich  Diaphragmus  elegans    (N.  and  P.) 

Pentremites  okawensis  n.sp.  Camarophoria     explanata      (McChes- 

Pentremites  canalis  Ulrich  ?  ney) 

Zeacrinus  sp.  Spiriferina  spinosa   (N.   and  P.) 

Eupachycrinus  sp.  Spiriferina   transversa    (McChesney) 

Pterotocrinus  sp.   (wing  plates)  Spirifer  increbescens  Hall,  var. 

Fistulipora  sp.  Spirifer  leidyi  N.  and  P. 

Fenestella  (several  species)  Reticularia  setigera    (Hall) 

Archimedes  swallovanus  Hall  Eumetria  vera  (Hall) 

Archimedes  distans  Ulrich  Cliothyridina  sublamellosa    (Hall) 

Septopora   subquadrans   Ulrich  Composita  trinuclea   (Hall) 


19G 


GEOLOGY  OF  HAnDIN  COUNTY 


In  Pope  County  a  number  of  collections  have  been  made  from  exposure 
northwest  of  Golconda,  within  a  radius  of  three  miles  from  that  town.  The 
combined  list  of  four  such  collections  is  as  follows : 


Fossils  from  the  Glen  Dean  limestone  collected  northwest  of  Golcondu 


Triplophyllum      spinulosum      (M.-E. 

and  H.) 
Pentremites  spicatus  Ulrich 
Pentremites  sp 

Pterotccrinus   sp.      (wing-plates) 
Fistulipora  sp. 
Meekopora  exirnia  Ulrich 
Eridopora  punctifera   Ulrich 
Batostomella  sp. 
Stenopora   tuberculata    (Prout) 
Fenestella   serratula  Ulrich 
Fenestella  sp. 

Archimedes  communis  Ulrich 
Archimedes   distans   Ulrich 
Archimedes  lerebriformis  Ulrich 
Polypcra  cestriensis  Ulrich 
Polypora  sp. 

Septopora  subquadrans  Ulrich 
Reteporina   flexuosa    (Ulrich) 
Streblotrypa  sp. 
Rhombopora  sp. 
Prismopora  serrulata  Ulrich 
Orbiculoidea  sp. 
Orthotetes     kaskaskiensis     (McChes- 


Productus  ovatus  Hall 
Productus  sp.  cf.  inflatus  McChesney 
Diaphragmus  elegans   (N.  and  P.) 
Pustula  punctata    (Martin)? 
Pustula  sp. 

Camarophoria     explanata      (McChes- 
ney) 
Rhynchopora  sp. 

Dielasma  shumardanum    (Miller) 
Girtyella  brevilobata    (Swallow) 
Spiriferina   spincsa   (N.  and   P.) 
Spiriferina   transversa    (McChesney) 
Spirifer  increbescens   Hall   var. 
Spirifer  leidyi  N.  and  P. 
Martinia  contracta  M.  and  W. 
Reticularis  setigera    (Hall) 
Eumetria  vera    (Hall) 
Cliothyridina    sublamellosa    (Hall) 
Composita  trinuclea   (Hall) 
Conularia  sp. 
Lioptera  sp. 
Platyceras  sp. 
Phillipsia  sp. 


ney) 

For  the  most  part  the  species  in  the  Glen  Dean  fauna,  as  exhibited  in 
Hardin  County  and  elsewhere,  are  more  or  less  widely  ranging  forms;  many 
of  them  would  not  be  out  of  place  in  any  Chester  fauna.  Among  the  species, 
however,  there  are  a  few  which  are  limited  in  their  geologic  range,  and  which 
may  be  considered  as  being  characteristic  of  this  horizon.  Among  such 
species  the  most  significant  one  in  the  Hardin  County  faunas  is  the  bryozoan 
Prismopora  serrulata,  which  may  be  found  in  practically  every  Glen  Dean 
fauna,  and  in  some  localities  it  is  a  very  common  form.  The  species  is  not 
wholly  limited,  however,  to  the  Glen  Dean  formation,  for  it  has  been  collected 
both  in  the  earlier  Golconda  fauna,  and  in  the  later  Vienna  limestone,  and 
even  in  the  Menard.  In  the  Golconda  limestone  it  is  very  rare  and  has  been 
observed  in  but  a  single  locality,  and  was  there  represented  by  a  single  speci- 
men. It  has  likewise  been  observed  in  the  Vienna  limestone  in  a  few  localities, 
in  Pope  and  Johnson  counties,  where  it  is  represented  by  a  much  larger 
number  of  examples  than  were  found  in  the  Golconda.  As  contrasted  with 
its  occurrence  in  these  older  and  younger  faunas,  the  species  is  conspicuous 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER    GROUP  197 

in  the  Glen  Dean.  In  places  in  this  formation  the  surfaces  of  certain  lime- 
stone layers  are  literally  Prismopora  gardens,  and  careful  search  brings  it  to 
light  in  practically  every  outcrop  of  any  size,  and  it  is  the  first  fossil  to  be 
sought  for  when  the  recognition  of  the  Glen  Dean  formation  is  involved. 
Another  fossil  species,  which  so  far  as  known  has  not  been  collected  outside 
of  the  Glen  Dean  formation,  is  the  large  Pentremites  spicatus.  This  species 
is  really  much  more  local  in  its  occurrence  than  the  Prismopora,  and  has  been 
observed  in  but  few  of  the  Hardin  County  collections,  although  it  has  been 
found  more  commonly  in  Pope  County  and  at  Carrsville,  Kentucky.  Another 
bryozoan  which  has  been  found  to  be  quite  characteristic  of  the  Glen  Dean 
horizon  in  Kentucky  and  elsewhere,  but  which  has  not  yet  been  observed  in 
either  Hardin  or  Pope  counties,  is  Archimedes  laxus,  and  the  peculiar  "wing- 
plates"  of  Pterotocrinus  bifurcatus  is  another  form  in  the  same  category. 
Any  one  or  all  of  these  species  may  be  sought  for  in  the  Glen  Dean  of  Hardin 
County. 

One  of  the  Glen  Dean  faunas  which  has  been  collected  from  a  limestone 
bed  in  the  upper  part  of  the  formation  in  Pope  County  is  quite  different  from 
those  in  which  the  Prismopora  is  commonly  met  with.  In  it  the  bryozoa  are 
practically  wanting,  and  it  is  especially  characterized  by  numerous  examples 
of  Martinm  contracta,  a  species  which  has  a  wide  range  in  the  Chester  faunas, 
but  which  is  especially  abundant  in  a  nearly  basal  zone  of  the  Okaw  limestone 
in  Randolph  County.  This  Martinia  fauna  has  not  yet  been  noticed  in  Hardin 
County,  but  it  would  not  be  surprising  to  find  it  there. 

CORRELATION 

A  comparison  of  the  fauna  of  the  Glen  Dean  formation  with  the  faunas 
of  the  Chester  group  in  Randolph  County,  shows  a  close  similarity  between 
this  fauna  and  that  of  the  upper  division  of  the  Okaw  limestone  in  the  more 
western  section.  In  both  faunas  the  bryozoan  Prismopora  serrulata  is  a 
characteristic  form ;  in  the  more  western  region  the  species  has  not  been  met 
with,  at  any  other  horizon  than  the  upper  Okaw,  and  in  the  southeastern  part 
of  the  state  it  has  been  met  with  only  rarely  in  any  other  horizon  than  the 
Glen  Dean.  In  both  regions  the  large  Pentremites  spicatus  is  known  only  at 
this  horizon.  A  number  of  other  characteristic  Glen  Dean  species,  such  as 
Archimedes  laxus,  and  Pterotocrinus  hifurcatus,  which  have  not  been' collected 
in  Hardin  County  but  which  are  known  in  Kentucky,  are  also  present  in  the 
jpper  Okaw  of  Randolph  County.  ■  With  so  many  features  in  common  between 
:he  Glen  Dean  and  the  upper  Okaw  faunas  the  correlation  of  the  two  forma- 
:ions  may  be  considered  as  established,  especially  as  they  occupy  corresponding 
30sitions  in  the  stratigraphic  series  of  the  two  regions. 

The  entire  assemblage  of  fossil  species  so  characteristic  of  the  Upper 
few-Glen  Dean  horizon,  occurs  also  in  the  Chester  beds  at  Sloans  Valley, 


198  GEOLOGY  OF  HARDIN  COUNTY 

Pulaski  County,  Kentucky,  in  the  southeastern  portion  of  the  state.  A  num- 
ber of  the  characteristic  species  were  first  described  from  the  Sloans  Valley 
locality,  and  there  can  be  no  question  of  the  presence  of  equivalent  strata  in 
the  Chester  section  at  that  locality;  but  data  are  not  available  to  determine 
whether  the  beds  are  limited  by  sandstone  formations  above  and  below,  as  in 
southeastern  Illinois. 


Tar  Springs  Sandstone 
name  and  distribution 


In  the  section  of  the  Chester  group  in  Breckenridge  County,  Kentucky 
the  limestone  and  shale  beds  that  are  characterized  by  Prismopom  semdaia 
and  Archimedes  laxus,  are  succeeded  by  a  massive  sandstone  formation.  One 
of  the  most  characteristic  features  of  this  sandstone  in  Breckenridge  County, 
Kentucky,  is  the  presence  in  it  of  springs  that  are  highly  charged  with 
bitumen.  Such  springs  are  locally  known  as  "tar  springs/'  and  the  name  Tar 
Springs  sandstone  was  used  for  the  formation  as  long  ago  as  1857  by  Owen.1 
Owen's  name  is  now  being  revived  and  is  applied  to  the  massive  sandstone 
formation  lying  next  above  the  Glen  Dean  limestone,  not  only  in  Breckenridge 
County,  Kentucky,  but  also  in  Kentucky  west  of  the  coal  fields,  and  in 
southern  Illinois.  The  formation  is  practically  coextensive  with  the  Glen 
Dean  formation  across  Hardin,  Pope,  Johnson,  and  into  Union  counties, 
Illinois,  and  in  the  adjoining  counties  in  Kentucky.  The  distribution  of  the 
Tar  Springs  sandstone  in  Hardin  County  is  similar  to  that  of  the  other 
Chester  formations.  The  sandstone  outcrops  as  one  of  the  outer  belts  en- 
circling that  portion  of  the  larger  dome  structure  that  is  included  in  the 
county,  extending  from  the  Ohio  Eiver  bluffs  near  the  southeastern  corner  of 
the  county  to  the  Hardin-Pope  County  line,  interrupted  at  intervals  by  xhe 
longer  northeast-southwest  faults,  the  greatest  interruption  being  made  by 
the  deeply  downdropped  block  of  Potts ville  that  extends  southwestwardly  to 
Keelin  School.  In  addition  to  this  more  regular  line  of  outcrop  there  are  a 
number  of  smaller  areas  occupied  by  the  formation  in  the  complexly  faulted 
region  northwest  of  Elizabethtown. 

In  the  southeastern  portion  of  the  county  the  Tar  Springs  sandstone  is 
limited  in  its  distribution  to  a  belt  extending  from  the  Ohio  Eiver  bluffs  west 
of  Honey  Creek,  northwestwardly  to  the  fault  bounding  the  central  faulted 
zone  on  the  southeast.  Throughout  this  belt  the  formation  occupies  the  north- 
easterly dipping  slopes  of  the  hills  lying  southwest  of  Honey  Creek  and  one 
of  the  tributaries  of  Eock  Creek. 

In  the  complexly  faulted  portion  of  belt  number  two  of  the  central 
faulted  zone,  the  Tar  Springs  sandstone  occupies  parts  of  a  number  of  the 
fault  blocks.     The  largest  of  these  areas  is  in  the  block  lying  southwest  of 


Geol.   Surv.  Ky.,  vol.   2,  pp.    86-87    (1857) 


UPPER    MISSISSIPPI  AN    SERIES,    CHESTER   GROUP  199 

Keelin  School,  the  outcrops  being  well  shown  along  the  Illinois  Furnace  road 
for  three-fourths  of  a  mile  northwest  from  the  junction  with  the  road  leading 
past  Keelin  School.  These  outcrops  continue  westward  from  this  road  for  a 
mile  or  more  to  the  wedge-shaped  western  extremity  of  the  block.  Adjacent 
to  the  valley  of  Big  Creek  the  Tar  Springs  is  mapped  as  constituting  a  part 
or  the  whole  of  a  number  of  small  blocks.  In  those  blocks  in  which  no  lime- 
stone is  present  to  assist  in  the  identification  of  the  formation,  the  Tar 
Springs  is  recognized  by  its  more  massive  character  as  compared  with  the 
other  formations.  In  belt  number  one  of  the  faulted  zone,  the  Tar  Springs 
occupies  its  normal  position  as  a  belt  extending  from  the  Wolrab  Mill  fault 
one  and  one-half  miles  southwest  of  Sparks  Hill  in  a  northwesterly  direction 
to  Harris  Creek. 

In  the  northwestern  portion  of  the  county  the  belt  of  the  Tar  Springs 
sandstone  occupies  its  normal  position  from  Rose  Creek  at  the  Hardin-Pope 
County  boundary,  to  the  Lee  fault  a  little  south  of  Loves  Store.  Eastward 
from  this  fault  the  formation  is  offset  to  the  southwest  for  a  mile  and  one-half, 
and  then  continues  eastward  to  the  Wolrab  Mill  fault. 

LITHOLOGIC    CHARACTER 

The  lithologic  characters  of  the  major  sandstone  formations  of  the  Chester 
group  in  southeastern  Illinois  are  so  much  alike  that  it  is  difficult  or  impos- 
sible to  differentiate  them  in  isolated  outcrops  where  the  stratigraphic  relations 
with  one  of  the  limestone  formations  of  the  section  are  not  shown.  Like  the 
Hardinsburg  and  Cypress  sandstones,  the  Tar  Springs  formation  is  a  yellowish- 
brown  sandstone,  becoming  distinctly  reddish  in  places.  It  contains  also 
some  very  white  layers  which,  however,  are  likely  to  be  stained  brown  on  the 
outside  by  the  surficial  oxidation  of  the  small  amount  of  iron  present.  On  the 
whole  the  color  is  more  like  that  of  the  Hardinsburg,  being  distinctly  less  pale 
than  much  of  the  Cypress.  In  texture  the  sandstone  is  moderately  fine 
grained,  not  essentially  different  from  the  other  two  formations  that  have 
been  mentioned. 

The  basal  portion  of  the  Tar  Springs  sandstone  consists  of  massive  beds 
which  locality  are  remarkably  cross-bedded,  the  individual  cross-bedded  units 
being  notably  saucer-shaped,  with  the  inclination  of  the  beds  sloping  in  all 
directions.  Cross-bedding  is  conspicuous  throughout  the  formation,  and 
ripple-marked  surfaces  and  other  surfaces  with  markings  indicating  shallow 
water  conditions  are  present  throughout  the  whole  of  it.  The  upper  portion 
of  the  formation  is  notably  more  thinly  and  more  evenly  bedded  than  the 
lower  part,  although  it  is  in  places  as  thickly  bedded  as  the  lower  part. 

In  the  midst  of  the  Tar  Springs  sandstone,  there  is  locally  at  least,  and 
perhaps  generally  throughout  Hardin  County,  a  shaly  member  which  may 
attain  a  thickness  as  great  as  forty  feet,  but  which  is  commonly  less  than 
that.     The  bed  is  composed  of  dark  to  black,  more  or  less  carbonaceous  shale, 


200  GEOLOGY    OF    HARDIN    COUNTY 

and  thinly  laminated  to  shaly,  fine-grained,  gray  sandstone,  coated  black  on 
the  surfaces  of  the  laminae  by  carbonaceous  matter.  Poorly  preserved  fossil 
plants,  mainly  undeterminable  stems,  occur  here  and  there  in  this  shale,  but 
in  a  shale  outcrop  in  the  road  side  at  Stone  Church,  two  miles  west  of  Eliza- 
bethtown,  which  is  probably  in  the  Tar  Springs,  numerous,  well  preserved 
fossil  plants  have  been  collected.  In  places  a  thin  bed  of  impure  coal  is 
associated  with  this  shale  member  of  the  Tar  Springs  sandstone,  one  of  its 
best  exhibitions  being  in  the  shallow  ravine  in  the  NE.  %  SE.  1,4  sec.  10,  T. 
12  S.,  E.  8  E.,  about  three  miles  north  of  Elizabethtown.  Another  exposure 
of  a  similar  coal  bed,  having  the  same  stratigraphic  position,  is  in  the  road 
midway  between  Pinhook  Creek  and  Rose  Creek,  in  the  NW.  %  sec.  14,  T. 
11  S.,  E.  7  E. 

THICKNESS 

In  none  of  the  exposures  in  Hardin  County  is  the  Tar  Springs  sandstone 
sufficiently  well  exposed  to  furnish  a  basis  for  a  satisfactory  determination  of 
its  thickness.  From  the  exposures  in  Pope  County,  however,  the  thickness 
can  be  estimated  with  some  degree  of  accuracy,  and  it  seems  to  exhibit  varia- 
tions between  100  and  150  feet.  A  similar  thickness  in  Hardin  County  may 
be  assumed.  From  this  it  will  be  seen  that  the  Tar  Springs  formation  js 
the  thickest  of  the  several  Chester  sandstone  formations  in  the  area. 

STRATIGRAPHIC   RELATIONS 

The  stratigraphic  relations  of  the  Tar  Springs  sandstone  with  the  under- 
lying Glen  Dean  limestone  can  only  be  inferred,  since  no  actual  exposure  of 
the  contact  between  the  two  formations  has  been  observed.  However  there 
seems  to  be  considerable  variation  in  the  thickness  of  the  Glen  Dean  forma- 
tion as  that  formation  has  been  studied  in  several  southern  Illinois  counties 
and  such  a  variation  suggests  an  erosion  period  preceding  the  deposition  of 
the  Tar  Springs  sandstone,  in  which  case  the  younger  formation  rests  uncon- 
formable upon  the  older.  The  existence  of  such  a  relation  between  these 
two  formations  would  be  in  conformity  with  the  relations  between  the  other 
Chester  sandstones  and  their  subjacent  limestone  formations,  since  in  every 
case  where  the  actual  contact  between  such  beds  has  been  observed,  evidences 
of  unconformity  are  exhibited. 

Our  knowledge  from  actual  observation,  of  the  upper  contact  of  the  Tar 
Springs  sandstone  is  just  as  unsatisfactory  as  that  of  the  lower  one.  Through- 
out the  county  and  also  in  the  immediately  adjoining  region  the  interval 
between  this  formation  and  the  overlying  Menard  limestone  is  uniformly 
covered.  The  absence  however,  ■  of  the  Vienna  limestone  and  Waltersburg 
sandstone  throughout  Hardin  County,  as  contrasted  with  their  presence  in 
counties  to  the  west,  may  indicate  an  unconformity  in  Hardin  County  above 
the  Tar  Springs  sandstone. 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  201 

PALEONTOLOGY 

The  only  fossils  that  have  been  observed  in  the  Tar  Springs  formation 
in  Hardin  County,  are  plant  remains.  Butts  has  found  a  single  determinable 
fragment  of  a  fossil  fern  in  the  median  shale  member  of  the  formation,  about 
one-half  mile  east  of  Eose  Creek  School,  in  a  ravine  south  of  the  road  in  the 
SW.  %  sec.  11,  T.  11  S.,  E.  7  E.  This  specimen  has  been  identified  by  David 
White  as  a  species  of  Cardiopteris,  probably  C.  pohjmorpha.  The  plant-bearing 
shale  exposure  in  the  roadside  at  Stone  Church,  already  mentioned,  is  in  a 
small  fault  block  in  which  no  limestone  formation  is  exposed,  so  that  the  age 
of  the  sandstone  formation  in  which  the  shale  is  included  is  not  determinable 
with  certainty.  However,  of  all  the  sandstone  formations  known  to  be  present 
in  the  county,  such  a  shale  member  conforms  best  with  the  Tar  Springs.  The 
plants  from  this  locality  are  not  numerous  specifically,  but  the  specimens  are 
abundant  and  well  preserved,  although  fragmentary.  The  forms  that  have 
been  identified  by  David  White  are  as  follows: 

Fossils  collected  from  the  middle  shale  member  of  the  Tar  Springs  formation 

Cardiopteris  polymorpha  Gopp  Lepidodendron  sp.  undet. 

Sphenopteris  sp.  undet. 

It  is  significant  that  the  species  of  Cardiopteris  which  is  recognized  in 
this  collection,  is  the  same  as  the  one  which  has  been  identified  from  the 
undoubted  Tar  Springs  east  of  Eose  Creek  School.  The  excellent  condition 
of  preservation  of  these  fossil  plants,  which  were  of  course  living  upon  the 
land  at  that  time,  shows  that  they  could  have  been  transported  no  great 
distance,  and  consequently  that  the  land  surface  where  they  grew  must  have 
been  near  at  hand. 

CORRELATION 

In  Breckenridge  County,  Kentucky,  the  same  species  of  Cardiopteris  that 
has  been  identified  in  Hardin  County,  is  known  from  the  typical  Tar  Springs, 
and  associated  with  it  is  a  Lepidodendron  comparable  with  the  one  recorded 
from  Stone  Church.  Such  evidence  helps  to  corroborate  the  correlation  of 
this  sandstone  formation  in  the  two  regions.  Cardiopteris  polymorpha  is  also 
known  from  beds  regarded  as  middle  Chester  at  Abbs  Valley,  Virginia,  and 
it  is  found  in  the  Mississippian  of  Europe. 

In  the  Eandolph  County,  Illinois,  section  of  the  Chester  group,  the  upper 
Okaw  limestone,  which  is  the  equivalent  of  the  Glen  Dean  formation  of 
Hardin  County,  is  succeeded  by  the  Menard  limestone.  In  Hardin  County 
these  two  limestones  are  separated  by  the  thick  Tar  Springs  sandstone.  In 
the  Eandolph  County  section,  therefore,  the  position  of  the  Tar  Springs 
sandstone  is  in  the  unconformity  beneath  the  Menard  limestone,  the  sandstone 
itself  being  entirely  lacking  in  the  section.  A  comparison  of  the  western 
extension  of  the  Tar   Springs   with  the  earlier  Hardinsburg,   Cypress,   and 


202  GEOLOGY  OF  HARDIN  COUNTY 

Bethel  sandstones,  shows  that  all  are  similar  in  regard  to  their  thinning  to  the 
west,  but  that  while  all  three  of  the  earlier  formations  have  at  least  some 
representation  in  Randolph  County,  the  Tar  Springs  sandstone  has  thinned 
out  entirely  and  disappeared. 

Vienna  Limestone  and  Waltersburg  Sandstone1 

In  Hardin  County  the  Tar  Springs  sandstone  is  succeeded  by  the  Menard 
limestone,  but  as  this  interval  is  traced  westward  two  important  formations, 
a  limestone  and  a  sandstone  are  found  to  be  intercalated  between  them.  These 
formations  have  been  designated  the  Vienna  limestone  from  excellent  ex- 
posures at  Vienna,  in  Johnson  County,  and  the  Waltersburg  sandstone  from 
the  exposures  of  the  beds  at  Waltersburg,  in  Pope  County.  Although  neither 
of  these  formations  has  been  definitely  recognized  in  Hardin  County,  both 
are  known  to  be  present  in  the  eastern  part  of  Pope  County,  in  that  portion 
of  the  county  included  in  the  accompanying  map  (Plate  I),  and  good  ex- 
posures of  them  may  be  seen  in  the  lower  part  of  the  bluff  having  a  general 
north-south  direction  near  the  middle  line  of  sees.  8  and  17,  T.  12  S.,  R.  7  E., 
below  Grandview  School.  The  limestone  is  commonly  a  highly  siliceous  or 
cherty  bed,  and  the  sandstone  resembles  the  other  sandstones  of  the  Chester 
series.  In  the  ridge  whose  extremity  lies  in  the  NE.  %  °^  sec-  8  just  men- 
tioned, and  which  extends  northward  into  the  adjoining  sec.  5,  the  Walters- 
burg sandstone  is  well  exposed  in  a  massive  outcrop.  In  the  Pope  County 
portion  of  the  geological  map  accompanying  this  report,  even  where  they  are 
known  to  be  present,  these  two  formations  have  not  been  mapped  separately 
from  the  Menard  limestone,  all  three  formations  being  included  in  the  same 
color.  When  these  units  were  first  observed  they  were  considered  as  subordi- 
nate members  of  the  Menard  formation,  but  as  the  field  studies  have  been 
carried  to  the  west  they  have  proven  to  be  equal  in  importance  and  magnitude 
with  other  Chester  units,  and  have  come  to  be  recognized  as  full  formations. 

It  is  altogether  probable  that  the  equivalent  of  the  Vienna  limestone  does 
continue  into  Hardin  County,  and  that  the  Waltersburg  sandstone  thins  out 
and  disappears  to  the  east,  bringing  the  Vienna  and  Menard  limestones  to- 
gether; and  it  is  not  unlikely  that  a  restudy  of  the  region  might  make  possible 
the  separation  of  the  Menard,  as  mapped,  into  its  probable  Vienna  and  Menard 
portions. 

Menard  Limestone 

name  and  distribution" 

The  Menard  limestone  has  been  described  from  Randolph  County,  Illi- 
nois, and  so  far  as  it  is  known  in  that  portion  of  the  state  its  surface  outcrops 


1  Written    in    October,    1919.    subsequent   to   the   mapping-   of   Hardin    County   and   the 
writing  of  the  major  portion  of  the  report. 


CHESTER   GROUP  203 

are  confined  to  that  county  and  Jackson  County.  The  typical  exposures  of 
the  formation  are  in  the  Mississippi  River  bluffs  between  Menard  and  Chester. 
The  formation  doubtless  extends  northward  from  Randolph  County,  but  in 
that  direction  it  is  completely  covered  by  the  overlapping  Pennsylvanian 
formations. 

In  the  southern  counties  of  Illinois  the  Menard  limestone  has  been  recog- 
nized in  its  proper  stratigraphic  position  across  Union,  Johnson,  Pope,  and 
Hardin  counties,  and  it  is  also  known  southward  across  Ohio  River  in  Critten- 
den and  some  of  the  adjacent  counties  in  Kentucky. 

In  Hardin  County  the  Menard  limestone  has  an  areal  distribution  similar 
to  that  of  the  older  Chester  formations.  In  the  southeastern  portion  of  the 
county  the  formation  occupies  a  belt  from  the  Ohio  River  bluffs  above  Honey 
Creek,  extending  northwestwardly  along  the  northeastern  wall  of  Honey  Creek 
valley  and  of  the  valley  of  a  tributary  of  Rock  Creek,  to  the  fault  limiting 
the  central  faulted  zone  of  the  county. 

In  belt  number  two  of  the  central  faulted  part  of  the  county  (see  figure 
3),  the  Menard  limestone  is  exposed  in  a  number  of  fault  blocks.  Good  ex- 
posures of  the  formation  are  present  along  the  east  side  of  the  road  past 
Keelin  School,  a  short  distance  north  of  the  junction  of  this  road  with  the  Illi- 
nois Furnace  road.  This  outcrop  continues  eastward  for  about  half  a  mile  and 
occupies  the  southern  border  of  a  trapeziform  fault  block.  A  little  north  of 
the  last  mentioned  outcrop,  on  the  west  side  of  the  road,  another  belt  of 
Menard  limestone  sets  in  and  continues  in  a  westerly  direction  across  a  larger 
trapeziform  fault  block.  Through  most  of  its  course  this  last  belt  is  heavily 
covered,  so  that  actual  outcrops  are  not  commonly  met  with.  The  black  shale 
exposed  in  the  Illinois  Furnace  road  on  the  line  between  the  sees.  10  and  11, 
T.  12  S.,  R.  8  E.,  is  the  basal  black  shale  member  of  the  Menard.  The  best 
exposure  of  the  formation  in  this  complexly  faulted  region  occurs  along  the 
road  running  north  from  Stone  Church  to  Illinois  Furnace.  The  extent  of 
this  outcrop  is  about  one  and  one-fourth  miles  in  a  north-south  direction, 
along  the  eastern  edge  of  the  larger  fault  block  that  extends  westward  to 
Wallace  Branch.  Smaller  outcrops  of  the  formation  along  the  eastern  margin 
of  this  same  fault  block  are  present  in  the  valleys  marking  the  fault  line  in 
a  southwesterly  direction  from  Stone  Church.  Another  Menard  limestone 
outcrop  occurs  along  the  road  to  Illinois  Furnace  at  the  northeastern  end  of 
Stone  Hill,  in  the  NE.  %  sec.  17,  T.  12  S.,  R.  8  E.  A  number  of  smaller 
patches  of  the  Menard  are  present  in  some  of  the  smaller  of  the  fault  blocks 
of  the  region.  In  the  small  Chester  area  which  is  mostly  included  in  sec.  21, 
T.  11  S.,  R.  9. B.,  in  fault  contact  with  the  Pottsville  to  the  northwest  and  in 
stratigraphic  contact  with  the  same  formation  on  the  southeast,  the  Menard 
occupies  a  belt  about  one  and  one-half  miles  in  length. 


204  GEOLOGY  OF  HARDIN  COUNTY 

In  belt  number  one  of  the  central  faulted  zone,  the  Menard  limestone 
occupies  its  normal  position  in  the  Chester  series,  from  the  Wolrab  Mill  fault 
one  mile  south  of  Sparks  Hill,  in  a  northeasterly  direction  to  the  Hogthief 
Creek  fault.  Other  small  areas  of  the  Menard  are  present  in  a  small  fault 
block  within  this  belt,  which  lies  mostly  in  sees.  19  and  20,  T.  11  S.,  E.  9  E. 

The  Menard  limestone  in  the  northwestern  portion  of  the  county  occupies 
a  narrow  belt  from  one-half  to  one  and  one-half  miles  south  of  the  county 
line,  along  the  valley  of  Bose  Creek  for  most  of  the  distance,  from  the  Pope- 
Hardin  County  line  to  the  Lee  fault,  just  south  of  Loves  Store.  Beyond  this 
to  the  east,  the  formation  is  offset  about  one  mile  to  the  southwest  and  then 
continues  eastward  to  the  Wolrab  Mill  fault,  along  a  valley  tributary  to  Big 
Creek. 

LITHOLOGICAL    CHARACTERS 

The  Menard  formation  in  Hardin  County  is  made  up  of  shale  and  lime- 
stone, the  limestone  predominating.  The  limestone  layers  are  commonly 
deposited  in  beds  a  foot  or  so  in  thickness,  which  are  separated  by  shaly 
partings.  In  the  basal  part  of  the  formation  there  is  a  much  thicker  body  of 
shale,  commonly  dark  in  color  and  in  places  black  with  carbonaceous  matter, 
and  locally,  at  least,  with  an  impure  coal  bed  a  few  inches  thick.  This  basal 
shale  bed  attains  a  possible  thickness  of  25  feet,  and  is  well  exhibited  at  the 
road  junction  in  the  SW.  y±  sec.  11,  T.  12  S.,  E.  8  E.,  about  two  and  one-half 
miles  north  of  Elizabethtown,  and  is  again  exposed  along  the  Illinois  Furnace 
road  about  one-half  mile  west  of  the  same  road  junction.  This  shale  is  also 
well  shown  in  an  exposure  on  Harris  Creek  about  one  mile  southeast  of  Sparks 
Hill,  in  the  SE.  %  NW.  1/4  sec.  18,  T.  11  S.,  B.  9  E.,  and  in  the  SE.  y4 
NW.  %  sec.  21,  T.  11  S.,  E.  9  E.  At  the  latter  locality  the  shale  includes  an 
impure  coal  bed  four  inches  thick,  which  lies  about  ten  feet  above  the  bottom, 
and  also  a  thin  layer  of  iron  carbonate  a  little  below  the  coal. 

The  limestone  of  the  Menard  formation  is  mostly  a  dense,  fine-grained, 
compact  rock,  bluish,  dark  gray,  or  nearly  black  in  color.  The  weathered 
surfaces  of  the  outcrops  are  smooth,  and  are  commonly  lighter  in  color  than 
the  freshly  broken  surfaces,  in  most  places  being  light  gray  or  bluish.  A 
relatively  small  proportion  of  the  limestone  is  rather  argillaceous  and  some- 
what ferruginous,  weathering  to  a  yellowish  or  buff  color.  In  its  lithologic 
characters  the  Menard  limestone  is  in  rather  strong  contrast  with  the  Glen 
Dean  and  Golconda  formations,  its  smoothly  weathering  surfaces  and  dense, 
compact  texture  being  very  different  from  the  rough,  even  crumbly  weathered 
surfaces,  and  the  granular,  or  crystalline  texture  of  the  two  older  formations. 
Crystalline  beds,  however,  are  not  entirely  lacking  in  the  Menard,  but  they 
are  unusual.  Although  the  Menard  is  comparatively  free  from  chert  in 
Hardin  County,  and  in  many  localities  none  at  all  is  present,  locally  a  small 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER    GROUP  205 

amount  is  found  in  the  form  of  thin,  platy  layers  which  are  more  or  less 
discontinuous. 

The  limestone  beds  of  the  Menard  are  commonly  fossiliferous,  but  in 
most  places  sparsely  so,  and  the  fossils  are  apt  to  be  so  firmly  imbedded  in 
the  rock  that  it  is  not  easy  to  collect  good  specimens.  Some  of  the  calcareous, 
shaly  partings  between  denser  limestone  layers,  however,  do  have  a  consider- 
able number  of  well-preserved  fossils  in  places. 

In  Hardin  County  no  sandstone  member  has  been  observed  in  the 
Menard,  but  in  tracing  the  interval  limited  by  the  Tar  Springs  sandstone 
below  and  the  Palestine  sandstone  above,  westward  into  Pope  County  and  still 
farther  into  Johnson  County,  a  conspicuous  chertv  limestone  formation  is 
developed  beneath  the  basal  shales  which  have  been  described,  and  a  sand- 
stone formation  between  the  shales  and  the  main  body  of  limestone  above. 
This  sandstone  begins  in  eastern  Pope  County  as  a  very  thin  stratum,  but 
thickens  to  the  west,  and  in  eastern  Johnson  County  it  increases  to  a  massive 
sandstone  formation  which  attains  a  thickness  of  fifty  feet  or  more.  Whether 
these  two  units  should  be  included  as  members  in  a  larger  formation,  along 
with  the  beds  here  designated  as  Menard,  or  should  be  defined  as  distinct 
formations  is  still  open  to  question.  In  connection  with  the  work  in  Pope 
and  Johnson  counties  the  name  Vienna  limestone  has  been  applied  to  the 
lower,  siliceous  limestone,  because  of  its  excellent  exposures  at  and  near  that 
town  in  Johnson  County,  and  the  sandstone  has  been  named  Waltersburg 
from  the  exposures  at  that  place  in  Pope  County.  The  main  limestone  mem- 
ber, as  developed  in  Hardin  County,  is  continuous  throughout  Pope  and 
Johnson  counties,  and  is  unquestionably  the  exact  equivalent  of  the  limestones 
to  which  the  name  was  Originally  applied  in  Eandolph  County. 

No  sections  through  the  entire  thickness  of  the  Menard  in  Hardin  County 
are  sufficiently  well  exposed  to  warrant  their  detailed  description.  In  one 
section  in  eastern  Pope  County,  however,  three  and  one-half  miles  north  of 
Golconda  on  the  road  to  Eaum,  in  the  adjoining  quarters  of  sees.  1,  2,  and  11, 
T.  13  S.,  E.  6  E.,  the  beds  occupying  the  interval  between  the  Tar  Springs 
and  Palestine  sandstones,  are  well  exhibited,  and  may  be  recorded  in  this 
place.  The  lower  limestone  member  in  the  section  is  the  Vienna  limestone, 
and  the  shale  bed  ivTo.  2,  with  sandstone  layers  at  the  top  doubtless  represents 
the  Waltersburg  sandstone,  the  Menard  proper  being  beds  Nos.  3,  4,  and  5. 

Section  of  the  Vienna,  Waltersburg,   and  Menard  formations   three   and   one-half 

miles  north  of  Golconda 

Feet 
5.  Limestone,  with  shale  partings.  Limestone  beds  for  the  most  part  dense 
and  compact  in  texture,  gray  to  blue-black  in  color,  in  beds  one  foot  more 
or  less  in  thickness.  About  20  feet  partly  exposed  below,  40  feet  or  more 
of  loess-covered  slope  above  with  occasional  limestone  outcrops  and 
some  scattered   chert  fragments 00 


20G  GEOLOGY    OF    HARDIN    COUNTY 

Feet 

4.  Limestone,  compact,  dense  and  hard,  blue-gray  to  blue-black  in  color, 
weathering  yellowish  on  surfaces;  some  beds  in  the  lower  portion  filled 
with  fossils,  among  which  large  examples  of  Spirifer  increbescens  are 
conspicuous    20 

3.     Limestone,  thinly  bedded  with  much  calcareous  shale,  abundantly  fossil- 

iferous,  with  many  bryozoans  and  brachiopods 15 

2.  Shale,  fissile,  dark,  blue-black  in  color  in  lower  portion,  becoming  some- 
what arenaceous  above,  with  platy  sandstone  layers  at  the  top;  the  aren- 
aceous beds  are  olive  green  in  color  and  break  into  elongate,  sliver-like 
fragments     50 

1.  Limestone,  dark  gray  to  nearly  black  in  color,  in  part  dense  and  compact 
in  texture,  and  in  part  somewhat  crystalline,  weathering  to  a  rusty 
brown  color  on  the  surface,  deposited  in  beds  one  foot  or  more  in  thick- 
ness, with  much  chert  in  plate-  or  sheet-like  masses  two  or  three  inches 
thick.  The  chert  is  dark,  chocolate-brown  or  black  in  color,  it  breaks 
vertically  into  subcubical  fragments  whose  upper  and  lower  surfaces,  in 
contact  with  the  inclosing  limestone,  are  commonly  decomposed  to  the 
depth  of  about  one-half  inch,  the  weathered  zone  being  sharply  differ- 
entiated from  the  central  unmodified  portion 20 

THICKNESS 

The  thickness  of  the  Menard  limestone  cannot  be  directly  measured  with 
certainty  in  Hardin  County,  owing  to  conditions  of  outcrop,  but  the  best  esti- 
mates indicate  a  thickness  of  from  80  to  120  feet.  In  the  Pope  County  section 
that  has  been  recorded,  165  feet  of  sediments  are  included,  but  the  Vienna 
limestone  is  well  represented  in  the  basal  part  of  the  section,  and  the  be- 
ginnings of  the  Waltersburg  sandstone  are  also  there ;  the  upper  portion  of  the 
section  that  may  be  strictly  considered  as  Menard  has  a  thickness  of  95  feet. 

STRATIGuAPHIC    RELATIONS 

As  in  the  case  of  many  of  the  other  Chester  formations  in  southeastern 
Illinois,  the  contacts  between  the  Menard  limestone  and  the  superjacent  and 
subjacent  formations  are  obscured  by  talus  or  other  surficial  deposits  in  every 
section  that  has  been  observed.  The  fact  that  the  upper  portion  of  the  sub- 
jacent Tar  Springs  sandstone  becomes  more  thinly  bedded  than  it  is  below, 
suggests  the  possibility  of  a  gradual  transition  from  the  sandstone  through 
arenaceous  shales  to  more  calcareous  shales  and  limestone,  but  the  field  evi- 
dence available  is  altogether  inconclusive.  There  is  apparently  no  stratigraphic 
break  between  the  several  members  of  the  formation — at  least  that  is  true  in 
the  best  and  most  continuous  sections  that  have  been  studied — and  the  con- 
dition probably  prevails  throughout  the  entire  region.  The  transition  from 
the  Menard  limestone  into  the  superjacent  Palestine  sandstone  is  as  obscure 
as  is  that  at  the  base  of  the  formation.  No  section  has  been  observed  where 
the  contact  between  these  two  formations  is  exposed,  but  if  the  conditions 
governing  the  beginning  of  the  deposition  of  the  sand  of  the  Palestine  forma- 


UPPER    MISSISSIPPIAN    SERIES,    CHESTER   GROUP 


20? 


tion  resemble  those  initiating  the  deposition  of  the  older  Chester  sandstones, 
viz.,  the  Bethel  and  the  Hardinsburg,  whose  lower  contacts  have  been  observed, 
then  the  Palestine  rests  unconformably  upon  the  Menard.  Perhaps  another 
line  of  evidence  bearing  upon  this  same  question  is  the  variation  in  thickness 
of  the  Menard.  While  this  variation  is  not  considerable,  it  may  be  due  to  the 
erosion  of  the  upper  surface  of  the  formation  preceding  the  deposition  of  the 
Palestine  sandstone.  In  the  southeastern  portion  of  the  county  a  distinct 
unconformity  at  the  summit  of  the  Menard  is  certainly  present,  for  the  higher 
Chester,  Palestine,  and  Clore  formations  are  wanting,  and  the  Pennsylvanian 
Pottsville  beds  rest  upon  the  Menard,  according  to  the  observations  of  Butts. 

PALEONTOLOGY 

The  most  prolific  fossil  fauna  from  the  Menard  limestone  in  Hardin  or 
Pope  counties,  occurs  in  the  basal  portion  of  the  formation.  Where  this  bed 
is  well  exposed  fossils  in  abundance  can  be  collected.  Nowhere  in  Hardin 
County  has  a  good  exposure  of  the  bed  been  met  with,  but  in  the  Pope  County 
section  which  has  been  described  above,  this  horizon  is  exposed  in  a  glade-like 
surface,  and  a  good-  collection  has  been  secured.  The  following  species  have 
been  identified  from  this  locality: 


Fossils  from  the  Menard  limestone  collected  three  and  one-half  miles  north  of 

Golconda 


Triplophyllum      spinulosum      (M.-E. 
and  H.) 

Pentremites  fohsi  Ulrich 

Hydreionocrinus  sp. 

Agassizocrinus  sp.   (bases) 

Pterotocrinus  menardensis  n.sp. 

Crinoids    (several    fragmentary    spe- 
cies) 

Archaeocidaris  (plates  and  spines) 

Fistulipora  excelens  Ulrich 

Eridopora  punctifera  Ulrich 

Meekopora  sp. 

Batostomella  ?  sp. 

Stenopora  cestriensi?  Ulrich 

Stenopora  sp. 

Stenopora  sp. 

Fenestella  serratula  Ulrich 

Fenestella    (several   undetermined 
species) 

Archimedes  swallovanus  Hall 

Archimedes  distans  Ulrich 

Archimedes  meekanus  Hall 

Archimedes  proutanus  Ulrich,  var 


Lyropora  sp.    (bases) 
Septopora  cestriensis  Ulrich 
Rhombopora  sp. 
Streblotrypa  distincta  Ulrich 
Bryozoan    (genus   and   species    unde- 
termined) 
Crania  chesterensis  M.  and  G. 
Orthotetes     kaskaskiensis      (McChes- 

ney) 
Productus   ovatus   Hall 
Diaphragmus  elegans  (N.  and  P.) 
Camarophoria     explanata      (McChes- 
ney) 
Dielasma  shumardanum    (Miller) 
Spiriferina    transversa    (McChesney) 
Spiriferina  spinosa    (N.  and  P.) 
Spirifer  increbescens  Hall 
Reticularia  setigera   (Hall) 
Eumetria  costata  (Hall) 
Cliothyridina  sublamellosa  (Hall) 
Composita  subquadrata    (Hall) 
Myalina  sp. 
Allorisma  clavatum   McChesney 


208  GEOLOGY  OF  HARDIN  COUNTY 

Archimedes  terebriformis  Ulrich  Sulcatopinna     missouriensis      (Swal- 

Polypora  corticosa  Ulrich  low) 

Polypora  tuberculata  Proul  Conularia  sp. 

Polypora  sp.  Phillipsia  sp. 

The  above  fauna  may  be  taken  as  typical  of  this  horizon  of  the  Menard 
Jimestone  throughout  southeastern  Illinois.  Several  of  the  species  in  the 
fauna  are  characteristic  of  this  zone  as  it  has  been  recognized,  not  only  in 
Pope,  but  in  Johnson  and  Union  counties,  while  others  are  commonly  met 
with  in  most  Chester  faunas.  A  single  species  of  Pentremites  is  recorded, 
P.  fohsi,  a  large  form  but  not  so  large  as  P.  obesus  from  the  basal  Golconda. 
This  species  has  been  met  with  wherever  any  considerable  collection  from  this 
zone  has  been  made  in  southern  Illinois  from  Union  to  Hardin  counties,  and 
it  has  not  been  collected  from  any  other  horizon.  Among  the  crinoids  a 
species  of  Pteroto crimes ,  represented  only  by  the  "wing  plates,"  has  been 
found  to  be  very  characteristic.  The  members  of  this  highly  specialized  genus 
have  proven  to  be  excellent  horizon  markers  in  the  Chester  group,  the  small 
spatulate  plates  with  serrate  border  in  the  Paint  Creek,  the  massive,  sub- 
globose  plates  of  P.  capitalis  in  the  Golconda,  the  peculiar  bifid  plates  of 
P.  bifurcatus  in  the  Glen  Dean,  and  now  again  in  the  Menard  these  very  large, 
flattened,  subcircular  plates  of  a  new  species,  P.  mena/rdensis,  which  is  allied 
to  P.  spatulatus.  The  detached,  spinose,  summit  plates  of  a  species  of 
Hydreionocrinus  have  been  collected  in  abundance  from  this  horizon  at  a 
number  of  localities,  being  met  with  much  more  commonly  at  this  horizon 
than  anywhere  else  in  the  Chester  series  of  southeastern  Illinois.  Likewise 
the  plates  and  spines  of  the  echinoid  genus  Archaeoddaris  are  more  commonly 
met  with  in  this  portion  of  the  Menard  than  at  any  other  Chester  horizon  in 
the  region.  The  bryozoans  are  represented  by  the  same  genera  and  mostly  by 
the  same  species  that  are  present  in  other  Chester  faunas.  Among  the 
brachiopods  most  of  the  species  are  commonly  present  in  other  Chester 
horizons,  but  the  typical  Spwifer  increbescens,  larger  and  coarser  in  appear- 
ance than  the  representatives  of  the  same  species  in  earlier  faunas,  is  abund- 
ant, and  the  smaller  Camposita  trinwelea  is  displaced  by  the  larger  and  broader 
C.  subquadrata.  The  form  of  Eumetria  that  is  commonly  met  with  in  this 
horizon  is  the  E.  costata,  a  larger  and  coarser  form  than  the  E.  vera  which 
was  the  usual  member  of  the  genus  in  the  older  faunas.  The  presence  of  the 
pelecypod  Sulcatopinna  missouriensis  is  a  very  characteristic  mark  of  the 
Menard  formation. 

The  higher  beds  of  the  Menard  are  much  less  fossiliferons  than  the 
lower  zone  which  has  afforded  the  fauna  that  has  been  recorded.  These  dense, 
compact  limestone  beds  are  not  well  adapted  for  the  preservation  of  fossils 
in  good  condition.  Some  of  the  shaly  partings  are  fossiliferons,  but  nowhere 
have  the  specimens  been  observed  to  be  so  well  preserved  or  so  abundant  as 
in  the  basal  zone  of  the  member.     Some  of  the  less  compact  limestone  beds  do 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER    GROUP  209 

locally  contain  numbers  of  the  large  Spirifer  increbescens  and  Composita  sub- 
quadrata,  and  in  places  the  highly  characteristic  Svlcaio pinna  missonriensis 
is  present  in  considerable  numbers.  This  species  is  an  elongate,  wedge-shaped 
shell,  some  large  examples  being  six  inches  or  more  in  length,  with  a  width  of 
two  inches  at  the  broader,  posterior  extremity.  Where  the  species  occurs  in 
its  usual  position  it  is  imbedded  vertically  in  the  limestone  with  the  pointed 
end  down,  and  it  doubtless  lived  in  that  position  in  the  calcareous  mud  of 
the  ancient  sea  bottom.  On  the  weathered  surfaces  of  the  limestone  ledges 
the  subelliptical  cross-sections  of  the  shells  may  be  seen  in  favorable  situations. 

CORRELATION" 

The  character  of  the  series  of  sediments  occupying  the  interval  between 
the  Tar  Springs  and  the  Palestine  sandstones  in  Hardin  County,  closely 
resembles  the  series  of  beds  occupying  the  interval  between  the  Okaw  lime- 
stone and  the  Palestine  sandstone  in  Eandolph  County.  In  following  this 
interval  westward  from  Hardin  County,  the  Vienna  limestone  and  the  Wal- 
tersburg  sandstone  make  their  appearance  below  the  main  body  of  Menard 
limestone,  but  both  of  these  have  disappeared  from  the  section,  along  with 
the  underlying  Tar  Springs  sandstone,  in  Eandolph  County.  The  main  body 
of  limestone,  as  developed  in  Hardin  County  is  clearly  continuous  westward, 
and  is  undoubtedly  the  exact  equivalent  of  the  typical  Menard  limestone  in 
the  Mississippi  Eiver  section.  While  no  such  prolific  fauna  with  Pentremites 
folisi,  such  as  has  been  recorded  from  Pope  County,  and  traces  of  which  have 
been  observed  in  Hardin  County,  has  been  observed  in  Eandolph  County,  the 
general  fauna  of  the  formation,  with  Sulcatopinna  missonriensis,  the  large 
Composita  subquadrata  and  Spirifer  increbescens,  is  present  throughout.  -  The 
lithologic  character  of  these  beds,  also,  is  remarkably  similar  throughout  the 
whole  extent  of  the  formation,  the  only  noticeable  difference  between  the  lime- 
stones of  Pope  and  Hardin  counties  and  those  of  Eandolph  County  being  the 
somewhat  darker  color  of  the  rock  from  the  southeastern  part  of  the  state. 
When  all  the  data  are  considered  there  seems  to  be  no  question  as  to  the  exact 
correlation  of  these  beds  entirely  across  the  state. 

Palestine  Sandstone 
name  and.  distribution 
The  Palestine  sandstone,  like  the  Menard  limestone,  was  originally  named 
rom  Eandolph  County,  Illinois.  The  sandstone  is  well  exposed  in  the  Missis- 
sippi Eiver  bluffs  in  the  neighborhood  of  Chester,  where  it  was  evidently 
•onsidered  by  some  of  the  earlier  workers  to  be  the  lower  portion  of  the  "Coal 
Aleasures."  It  was  to  this  sandstone  that  the  name  Chester  was  originally 
pplied  by  Shumard1,  and  if  the  strict  law  of  priority  were  followed  Chester 

1  Proc.  Amer.  Ass.  Adv.  Sci.,  vol.  11,  pt.  2,  p.  5    (1858). 
—14  G 


210  GEOLOGY    OF    HARDIN    COUNT!' 

as  a  group  name  would  be  abandoned.  The  name  has  become  so  fully  estab- 
lished in  literature,  however,  that  it  would  be  very  unwise  to  attempt 
to  change  it  at  this  time,  the  renaming  of  the  sandstone  formation  being  far 
more  desirable. 

In  the  Mississippi  Valley  counties  the  Palestine  sandstone  has  been  recog- 
nized only  in  Eandolph  and  Jackson.  In  the  more  southern  counties  of  the 
state  the  formation  has  been  recognized  across  Union,  Johnson,  Pope,  and 
Hardin  counties.  The  formation  extends  southward  across  Ohio  River  into 
Crittenden  and  adjacent  counties  in  Kentucky,  but  it  is  not  conspicuously 
developed  east  of  the  western  Kentucky  coal  basin. 

According  to  Butts,  the  Palestine  sandstone  is  not  now  present  in  the 
southeasterly  part  of  Hardin  County,  and  if  it  and  the  higher  Chester  forma- 
tions were  ever  deposited  there,  they  were  removed  by  erosion  before  the 
Pottsville  sediments  were  laid  down. 

In  the  central  faulted  zone  of  the  county  (see  figure  3)  the  Palestine 
sandstone  is  exposed  in  belt  number  two  in  a  number  of  the  fault  blocks  in 
the  area  lying  between  Keelin  School  and  Ohio  River.  Just  south  of  Keelin 
School  it  is  exposed  in  an  east-west  belt  in  a  small  block,  with  Menard  lime- 
stone to  the  south  and  the  Clore  formation  to  the  north.  The  east-west  hill 
lying  along  the  northern  border  of  the  SE.  %  sec.  11,  T.  12  S.,  R.  8  E.,  is 
capped  with  the  Palestine  sandstone,  the  south  slope  of  the  hill  being  under- 
lain by  the  Menard,  although  there  are  few  exposures  of  the  limestone.  Just 
north  of  Stone  Church  there  are  two  fault  blocks  whose  surface  outcrops  are 
entirely  of  sandstone,  that  have  been  mapped  as  Palestine.  With  no  limestone 
formations  for  reference  there  is  of  course  a  possibility  of  error  in  such 
determinations,  but  the  lithologic  character  of  the  sandstone  resembles  the 
Palestine  more  closely  than  any  of  the  lower  sandstone  formations.  The  most 
extensive  Palestine  outcrop  in  the  region  extends  from  the  summit  of  the  hill 
north  of  Carmens  Store,  in  a  southwesterly  direction  to  the  river  bluffs  about 
three-fourths  of  a  mile  northwest  of  Fairview.  Through  the  entire  length  of 
this  block  the  strata  are  dipping  to  the  northwest,  with  the  Menard  limestone 
exposed  at  intervals  along  the  southeastern  border. 

In  belt  number  one  of  the  central  faulted  region,  the  Palestine  occupies 
its  normal  position  in  the  Chester  group,  between  the  Menard  and  Clore. 
The  strip  of  territory  occupied  by  the  formation  extends  from  the  Wolrab 
Mill  fault  a  half  mile  south  of  Sparks  Hill,  to  the  Hogthief  Creek  fault  just 
west  of  Carrs  Store. 

In  the  northwestern  portion  of  the  county  the  Palestine  occupies  a  narrow 
belt  extending  from  the  Pope-Hardin  County  line  a  little  north  of  Rose  Creek, 
to  the  Lee  fault  at  Loves  Store.  Eastward  from  here  it  is  offset  about  one 
mile  to  the  southwest,  and  then  continues  eastward  to  the  Wolrab  Mill  fault. 
The  district  underlain  by  the  formation  is  marked  by  knobs  and  ridges,  in 


UPPER   MISSISSIPPI  AN    SERIES,    CHESTER   GROUP  211 

contrast  with  the  low  ground  which  in  general  marks  the  outcrop  of  the 
underlying  Menard  limestone. 

LITHOLOGIC    CHARACTERS 

In  its  general  composition  the  Palestine  sandstone  is  more  thinly  bedded 
than  the  lower  Chester  sandstone  formations,  although  locally  it  does  con- 
tain rather  thick  bedded  layers.  Some  layers  are  distinctly  shaly,  but  the 
shales  are  arenaceous  in  character,  being  quite  unlike  the  clay  shales  which 
are  associated  with  some  of  the  older  sandstones.  Some  of  the  surfaces  are 
ripple-marked,  and  some  layers  exhibit  distinct  cross-bedding.  The  rock  is 
fine  grained  in  texture  and  yellowish-brown  in  color,  much  of  it  being  of  a 
paler  tint  than  most  of  the  Tar  Springs  and  Hardinsburg  sandstones.  In  its 
appearance  the  Palestine  sandstone  of  Hardin  County  more  nearly  resembles 
some  of  the  higher  sandstone  beds  of  the  Chester  than  it  does  the  older 
Chester  sandstones,  and  in  places,  where  no  limestone  is  exposed,  it  is  difficult 
or  impossible  to  know  whether  certain  beds  should  be  referred  to  the  Palestine 
or  to  a  higher  position. 

THICKNESS 

The  Palestine  is  one  of  the  thinner  sandstone  formations  of  the  Chester 
section  in  southeastern  Illinois,  and  although  its  upper  and  lower  limits  have 
not  been  definitely  fixed  in  any  one  section,  reasonably  accurate  estimates  of 
its  thickness  can  be  made  in  a  number  of  situations  in  both  Hardin  and  Pope 
counties.  These  estimates  give  an  approximate  thickness  of  GO  feet,  although 
in  northwestern  Hardin  County  the  thickness  appears  to  be  fully  100  feet. 

STRATIGRAPHIC    RELATIONS 

Like  the  contacts  between  most  of  the  formations  in  Hardin  County,  that 
between  the  Palestine  and  the  underlying  Menard  is  commonly  obscured.  At 
one  locality  however,  near  the  top  of  the  hill  west  of  Carmens  Store,  in  the 
ravine  north  of  the  road,  the  contact  between  these  two  formations  is  fairly 
well  shown.  This  section  shows  that  the  change  from  the  limestone  to  the 
sandstone  is  abrupt,  with  no  intergrading  beds,  a  condition  which  suggests  an 
interruption  in  the  sedimentary  record  at  this  horizon.  The  exposure  of  the 
contact  is  not  sufficiently  broad  to  show  clearly  whether  there  are  other  evi- 
dences of  unconformity  here,  and  there  is  no  development  of  a  basal  con- 
glomerate exhibited.  It  is  not  unlikely,  however,  that  the  sedimentary  record 
was  interrupted  at  this  horizon,  and  that  the  Palestine  lies  unconformable 
upon  the  underlying  limestone.  Further  evidence  of  an  unconformitv  between 
these  two  formations  is  shown  in  the  Eandolph  County  section  where  both 
formations  were  originally  defined.  There  is  probably  no  physical  break  at 
the  top  of  the  Palestine. 


212  GEOLOGY    OF    HARDIN    COUNTY 

In  Bandolph  County,  where  both  the  Palestine  and  Clore  formations  were 
first  recognized,  there  is  apparently  no  stratigraphic  break  between  them,  the 
sandstone  passing  upward  through  sandy  shales  into  more  calcareous  shales, 
and  finally  into  limestones  and  shales  interbedded. 

PALEONTOLOGY 

The  only  fossils  which  have  been  met  with  in  the  Palestine  are  more  or 
less  fragmentary  tree  trunks  of  the  genus  Lepidodendron,  which  has  been 
identified  by  David  White  as  L.  cf.  modulatum. 

CORRELATION 

The  Palestine  is  the  first  of  the  Chester  sandstone  formations  that  is 
equally  well  developed  in  the  southeastern  Illinois  section  and  in  the  Randolph 
County  section.  In  both  regions  the  sandstone  formation  occupies  the  same 
position  in  the  section,  and  it  maintains  approximately  the  same  thickness 
throughout.  There  can  be  no  question  as  to  the  continuity  of  the  bed  through- 
out the  entire  Illinois  basin  of  Chester  time. 

Clore  Limestone1 
name  and  distribution 

The  Clore  formation  is  typically  developed  in  Bandolph  County,  where 
it  caps  some  of  the  higher  hills  east  of  Chester.  It  extends  beyond  Bandolph 
into  Jackson  County  to  the  southeast,  and  is  exposed  in  its  proper  strati- 
graphic  position  entirely  across  the  southern  portion  of  Illinois,  in  Union. 
Johnson,  Pope,  and  Hardin  counties,  but  it  becomes  thinner  and  less  con- 
spicuous in  its  eastward  extension. 

When  this  unit  was  originally  defined  it  was  believed  that  the  Clore  was 
the  highest  of  the  Chester  formations,  and  consequently,  during  the  field 
studies  in  Hardin  County  all  those  beds  between  the  Palestine  sandstone 
below  and  the  Pottsville  above  were  referred  to  it.  It  was  recognized,  however, 
that  this  series  of  strata  in  southeastern  Illinois  was  much  thicker  than  in 
the  typical  exposures,  and  that  it  included  an  important  sandstone  member 
between  two  limestones,  the  lower  of  which  is  much  the  thinner  and  less  con- 
spicuous. With  the  extension  to  the  south  and  east  into  Jackson  County,  of 
the  studies  of  the  Chester  group  in  the  Mississippi  Biver  section,  it  has  been 
found  that  the  Clore  limestone  is  succeeded  by  an  important  sandstone  forma- 

1  The  sections  of  this  report  on  the  Clore  limestone,  Degonia  sandstone,  and  Kinkaid 
limestone  have  been  written  after  the  close  of  the  1919  field  season.  Before  this  time 
all  three  of  these  units  have  been  considered  as  members  of  the  Clore  formation,  but 
later  observations  in  southeastern  Randolph  and  northwestern  Jackson  counties  by  Mr. 
J.  Marvin  Weller,  have  established  the  importance  of  these  higher  Chester  divisions,  ana 
have  led  to  their  recognition  as  distinct  formations  coordinate  in  rank  with  the  other 
units  of  the  Chester  group.  Upon  the  accompanying  map  all  three  of  these  formations 
are  included  under  a  single  color  with  the  Clore  symbol,  but  if  the  area  were  re-workea 
all  of  them  could  be  differentiated  in  much  or  all  of  the  area. 


UPPER   MISSISSIPPI  AN    SERIES,    CHESTER   GROUP  213 

tion  100  feet  or  more  in  thickness,  and  this  again  by  a  thick  limestone,  the 
two  having  been  named  the  Degonia  sandstone  and  the  Kinkaid  limestone 
respectively.  A  comparison  of  this  section,  and  of  the  fossil  faunas  of  the  two 
limestones,  with  the  uppermost  Chester  of  southeastern  Illinois,  has  estab- 
lished the  fact  that  the  Clore  limestone  is  properly  represented  in  Hardin  and 
Pope  counties  by  the  lower  limestone  member  only  of  the  formation  as  it  was 
originally  mapped. 

In  Hardin  County  the  Clore  limestone  as  now  restricted,  is  the  thinnest 
one  of  all  the  limestone  formations  of  the  Chester  group,  and  comparatively 
few  good  outcrops  of  the  formation  are  exposed.  An  outcrop  of  it  may  be 
seen,  appearing  beneath  the  overlying  Degonia  sandstone,  in  the  short  ravine 
situated  in  the  NW.  %  SW.  14  sec.  12,  T.  12  S.,  E.  8  E.,  three-fourths  of  a 
mile  southeast  of  Keelin  School.  It  is  again  exposed,  only  a  few  feet  thick,  in 
the  roadside  less  than  one-fourth  of  a  mile  south  of  Keelin  School,  here  again 
being  overlain  by  sandstone.  Two  and  one-half  miles  northwest  of  Elizabeth- 
town  an  inconspicuous  outcrop  of  limestone  by  the  road-side  in  the  SE.  14 
SE.  14  sec.  17,  T.  12  S.,  E.  8  E.,  is  believed  to  represent  the  Clore  limestone, 
and  from  this  point  it  extends  in  a  northeast  direction  through  the  extent  of 
the  small  fault  block  in  which  it  is  situated,  although  the  outcrops  are  meager. 
Another  exposure  may  be  seen  in  the  road-side  a  mile  west  of  Carmens  Store, 
north  of  Eosiclare.  One  of  the  best  exposures  of  the  formation,  and  the  only 
one  from  which  a  representative  fauna  has  been  collected  in  Hardin  County, 
is  situated  about  half  a  mile  southeast  of  Sparks  Hill,  in  the  xsrW.  ^4  sec-  18,  T. 
11  S.,  E.  9  E. 

According  to  Butts,  the  Clore  and  higher  Chester  formations  are  not 
exposed  at  all  in  the  southeastern  portion  of  Hardin  County,  the  pre-Pennsyl- 
vanian  unconformity  being  greater  in  this  part  of  the  county  than  elsewhere, 
in  consequence  of  which  the  Pottsville  sandstone  lies  in  contact  with  the 
Menard  limestone. 

LITHOLOGIC    CHARACTERS 

In  its  typical  exposures  in  Eandolph  County,  the  Clore  limestone  is 
exceedingly  variable  in  character,  and  includes  a  considerable  amount  of  shale. 
In  places  the  limestone  ledges  are  hard,  compact,  and  dense,  others  are  shaly 
with  more  or  less  carbonaceous  matter,  while  still  other  layers  are  somewhat 
crystalline.  In  color  the  different  layers  vary  from  gray  or  bluish  gray  to 
nearly  black.  The  shale  beds  commonly  constitute  a  considerable  portion  of 
the  total  thickness  of  the  formation,  in  places  more  than  one-half;  they  are 
completely  argillaceous  or  more  or  less  calcareous  in  character. 

In  Hardin  County  the  character  of  the  formation  is  similar  to  that  in  its 
typical  exposures.  The  shaly  character  of  the  limestone  layers  themselves, 
and  the  large  amount  of  argillaceous  and  calcareous  shales  associated  with  the 
limestones  is  a  feature  of  the  formation  wherever  exposures  of  it  can  be  seen 


214  GEOLOGY  OF  HARDIN  COUNTY 

Some  of  the  limestone  layers  are  filled  with  fragmentary  fossil  brachiopods, 
bryozoans,  which  are  commonly  so  broken  or  so  firmly  imbedded  that  it  is 
not  possible  to  identify  them  with  any  degree  of  satisfaction. 

THICKNESS 

In  Eandolph  County  the  maximum  thickness  of  the  Clore  limestone  is  50 
or  60  feet.  It  becomes  thinner  in  its  extension  to  the  southeast,  becoming  in 
most  of  Johnson  and  Pope  counties  but  30  or  40  feet.  In  Hardin  County 
it  seems  to  become  still  thinner,  and  probably  is  nowhere  more  than  20  or  30 
feet,  and  in  places  it  may  be  even  thinner  than  this. 

STRATIGRAPHIC    RELATIONS 

Because  of  the  thinness  of  the  formation  and  the  consequent  covering  of 
the  outcrop  by  surficial  deposits  the  actual  contacts  of  the  Clore  limestone  with 
the  underlying  and  overlying  sandstones  has  nowhere  been  observed,  and  the 
stratigraphic  relations  of  the  formation  with  its  bounding  sandstones  are  not 
known.  There  are  no  data  to  show  that  any  unconformity  exists  either  below 
or  above  the  formation,  and  it  is  quite  likely  that  it  constitutes  a  portion  of 
an  entirely  conformable  series  of  beds. 

PALEONTOLOGY 

All  of  the  limestone  beds  in  the  Clore  formation  contain  more  or  less 
fragmentary  fossils,  most  of  which  are  too  imperfect  to  be  determined.  From 
some  of  the  shaly  beds  better  fossils  can  be  collected.  The  only  important 
collection  that  has  been  made  in  Hardin  County  is  from  the  locality  about 
one-half  mile  southeast  of  Sparks  Hill,  in  which  the  following  species  have 
been  identified : 

Fossils  from  the  Clore  limestone  collected  near  Sparks  Hill,  Hardin  County 

Pterotocrinus  sp.   (wing  plate)  Camarcphoria     explanata      (McChes- 
Batostomella  nitidula  Ulrich  ney) 

Fenestella  serratula  Ulrich  ?  Dielasma  shumardiannm   (Miller) 

Fenestella  tenax  Ulrich  ?  Spiriferina    transversa    (McChesney) 

Archimedes  sp.  Spirifer  increbescens  Hall 

Productus  arkansanus  Girty  ?  Reticularia  setigera   (Hall) 

Diaphragmus  ?  sp.  Eumetria  costata  (Hall) 

;         Composita  subquadrata   (Hall) 

The  presence  in  this  fauna  of  the  large  and  broad  Composita  subquadrata 
marks  this  fauna  as  of  upper  Chester  age,  that  is  it  could  not  be  older  than 
the  Menard,  and  the  large  examples  of  Spirifer  increbescens  have  the  same 
significance.  Most  of  the  other  species  might  be  present  in  any  one  of  several 
other  Chester  horizons  although  the  rather  large  Productus  that  has  been 
referred  with  a  query  to  P.  arl'ansanus  has  not  been  observed  elsewhere.  The 
one   species  that  is  most  significant  is  the  -bryozoan  Batostomella  nitidula 


UPPER    MISSISSIPPI  A.N    SERIES,    CHESTER   GROUP  215 

This  little,  branching,  cylindrical  form  occurs  rather  commonly  upon  the 
surfaces  of  the  limestone  layers  at  this  locality  and  elsewhere  in  the  lower 
portion  of  the  Clore,  and  has  not  been  collected  by  the  writer  from  any  other 
horizon  in  southern  Illinois.  In  places  it  is  very  abundant,  the  broken  zoaria 
being  crowded  together  upon  the  surface  of  the  limestone  layers,  and  it  is 
perhaps  the  best  index  fossil  for  this  horizon. 

One  of  the  best  faunas  from  the  Clore  that  has  been  collected  in  south- 
eastern Illinois  is  from  a  locality  in  Pop#  County  about  four  miles  northwest 
of  Golconda.  The  stratigraphic  position  of  the  collection  in  the  formation  is 
between  30  and  40  feet  above  the  top  of  the  Palestine  sandstone,  and  the 
species  that  have  been  identified  are  as  follows : 

Fossils  from   the  Clore  limestone  collected  northwest  of  Golconda,  Pope  County 

Triplophyllum      spinulosum      (M.-E.         Streblotrypa  nicklesi  Ulrich 

and  H.)  Streblotrypa  sp. 

Pentremites  sp.  Crania  chesterensis  M.  and  G. 

Pterotocrinus  sp.   (wing  plates)  Orthotetes     kaskaskiensis     (McChes- 
Agassizoerinus  sp.   (base)  ney) 

Archaeocidaris  sp.    (spines   and  Productus  ovatus  Hall 

plates)  Productus  sp. 

Batostomella  nitidula  Ulrich  Diaphragmus  elegans    (N.  and  P.) 

Batostomella   (several  species)  Camarophoria     explanata      (McChes- 
Stenopora   cestriensis   Ulrich  ?  ney) 

Stenopora  sp.  Girtyella    indianensis    (Girty) 

Lioclema?  araneum  Ulrich  Spiriferina  spinosa  (N.  and  P.) 

Lioclema  sp.  Spiriferina    transversa    (McChesney) 

Fenestella  serratula  Ulrich  ?  Spirifer  increbescens  Hall 

Fenestella  elevatopora  Ulrich  ?  Reticularia  setigera   (Hall) 

Fenestella    (several  species)  Eumetria  costata   (Hall) 

Archimedes    (several  species)  Cliothyridina   sublamellosa    (Hall)? 

Polypora  approximata  Ulrich  Composita  subquadrata   (Hall) 

Polypora  sp.  Bellerophon  sp. 

Septopora  cestriensis  Ulrich  Euomphalus  sp. 

Rhombopora    (several  species)  Pleurotomaria  ?   sp. 

The  outstanding  features  of  this  fauna  are  the  abundance  of  the  delicate, 
branching,  cylindrical  bryozoans  belonging  to  the  genera  Batostomella  and 
Rhombopora.  Among  these,  Batostomella  nitidula  is  a  conspicuous  form,  and 
it  is  associated  with  large  numbers  of  the  large  and  broad  Composita  sub- 
quadrata. This  faunal  combination  is  characteristic  of  the  Clore  faunas 
throughout  southern  Illinois. 

CORRELATION 

The  essential  identity  of  the  Clore  fauna  in  Hardin  County  and  elsewhere 
in  southeastern  Illinois,  with  that  from  the  typical  exposures  of  the  formation, 
as  well  as  the  fact  that  the  formation  can  be  and  has  been  traced  almost  con- 


216  GEOLOGY  OF  HARDIN  COUNTY 

tinuously  across  the  state,  establishes  without  any  doubt  the  correlation  of 
these  beds  in  Hardin  County  with  the  original  Clore  limestone  of  Randolph 
County.  The  formation  is  not  so  thick  towards  the  east,  but  nevertheless  both 
its  lithologic  and  faunal  characters  remain  essentially  the  same  throughout 
the  whole  extent  of  the  formation. 

Degonia  Sandstone 
name  and  distribution 

The  Degonia  sandstone  has  been  named  from  Degonia  Township  in 
western  Jackson  County,  Illinois,  where  the  sandstone  is  a  conspicuous  cliff- 
making  sandstone  in  the  bluffs  of  the  Mississippi  River  and  especially  in  the 
sides  of  the  valleys  tributary  to  the  Mississippi.  The  formation  has  been 
traced  continuously  in  the  Mississippi  River  bluffs  to  the  intersection  of  the 
valley  of  the  Big  Muddy  River.  Where  this  sandstone  was  first  observed  in 
Randolph  County,  some  years  ago,  before  it  was  known  to  be  overlain  by  a 
thick  limestone  with  a  characteristic  Chester  fauna,  it  was  believed  to  be  the 
basal  member  of  the  Potts ville  formation  in  that  portion  of  the  state,  and  it 
has  been  included  in  the  Pottsville  in  the  mapping  of  the  Murphysboro 
quadrangle.1 

In  the  more  southern  counties  of  Illinois  this  sandstone  has  been  recog- 
nized across  Jackson,  Union,  Johnson,  and  Pope  counties,  although  in  the 
earlier  field  work  in  this  area  it  was  considered  as  a  member  of  a  more  compre- 
hensive Clore  formation.  This  and  the  Palestine  are  the  only  two  of  the  Chester 
sandstones  that  are  present  clear  across  the  state  from  Randolph  to  Hardin 
counties.  In  tracing  the  formation  to  the  southeast  it  retains  essentially  the 
same  characters  which  it  possesses  in  Randolph  and  Jackson  counties,  into 
Union  County.  Farther  to  the  east  it  becomes  somewhat  more  thinly  bedded 
and  less  massive,  and  this  character  persists  throughout  Hardin  County.  Much 
of  the  Degonia  sandstone  in  Hardin  County  resembles  the  Palestine  more  or 
less  closely,  and  it  is  possible  that  in  some  parts  of  the  county  the  Clore  has 
been  overlooked  where  it  is  thin  and  has  been  obscured  by  surficial  covering, 
and  that  the  Degonia  has  been  included  with  the  Palestine  in  the  mapping. 
The  formation  is  well  exhibited  in  the  hill  just  west  of  Iveelin  School,  three 
and  one-half  miles  northeast  of  Elizabethtown,  and  it  is  also  well  exposed  in 
the  hills  about  one-half  mile  southeast  of  the  same  school,  in  the  west  half 
of  sec.  12,  T.  12  S.,  R.  8  E.,  where  its  relation  to  the  Clore  limestone  may  be 
seen.  Other  good  exposures  of  the  Degonia  sandstone  are  present  in  the 
western  part  of  sec.  20,  T.  12  S.,  R.  8  E.,  along  the  road  west  from  Carmens 
Store,  two  and  one-half  miles  north  of  Rcsiclare.  At  this  locality  the  relation 
of  the  sandstone  to  the  underlying  Clore  limestone  may  be  seen,  and  the  sand- 


U.   S.   Geol.   Surv.,   Murphysboro-Herrin  Folio    (No.   185). 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER   GROUP  21? 

stone  itself  is  well  exposed  in  the  hills  south  of  the  road  in  the  same  section. 
The  most  notable  development  of  the  Degonia  sandstone  in  northern  Hardin 
County  is  a  third  of  a  mile  south  of  Sparks  Hill,  in  the  northern  part  of  the 
NE.  14  sec-  13>  T.  11  S.,  R.  8  E.,  where  there  is  a  massive  sandstone  layer  ten 
feet  or  more  thick  which  forms  a  pronounced  ridge  on  which  the  volcanic  plug 
of  that  locality  outcrops. 

LITHOLOGIC    CHARACTERS 

In  the  region  of  its  typical  occurrence  the  Degonia  is  a  very  massive, 
cliff -making  sandstone,  and  is  not  unlike,  in  any  respect,  many  of  the  pebble- 
less  sandstone  layers  of  the  Pottsville.  In  massiveness  the  formation  more 
nearly  resembles  the  Cypress  sandtone  of  the  more  southern  Illinois  counties, 
than  any  other  Chester  sandstone.  Locally,  however,  the  formation  does  con- 
tain rather  thick  strata  of  thinly  bedded  sandstones  which  are  conspicuously 
ripple-marked,  and  which  are  almost  arenaceous  shales  in  places.  Much  of  the 
formation  exhibits  notable  cross-bedding. 

The  texture  of  the  sandstone  in  its  typical  exposures  is  somewhat  coarser 
than  most  of  the  Chester  sandstones,  and  the  weathered  bluff  surfaces  not 
infrequently  exhibit  more  or  less  conspicuous  iron  crusts  similar  to  those 
present  in  the  Pottsville  sandstones  in  many  places.  The  color  of  the  sand- 
stone is  commonly  light  brown  upon  freshly  broken  surfaces,  but  becomes 
darker  upon  weathered  surfaces  through  the  oxidation  of  the  iron. 

THICKNESS 

In  its  typical  development  in  Randolph  and  Jackson  counties  the  Degonia 
sandstone  reaches  a  maximum  thickness  of  somewhat  more  than  100  feet,  and 
is  probably  nowhere  less  than  100  feet.  In  the  eastward  extension  of  the 
formation  it  becomes  somewhat  thinner,  and  in  Hardin  County  it  probably 
does  not  exceed  50  or  60  feet  in  any  section,  and  in  places  it  may  be  con- 
siderably less  than  this. 

STRATIGRAPHIC    RELATIONS 

No  observations  have  been  made  in  Hardin  County  to  indicate  that  the 
Degonia  sandstone  lies  in  other  than  conformable  relations  with  the  underly- 
ing Clore,  or  the  overlying  Kinkaid  limestones,  although  it  must  be  kept  in 
mind  that  it  has  not  been  possible  to  study  the  actual  contacts  between  these 
formations  in  any  section. 

PALEONTOLOGY 

Like  the  other  sandstones  of  the  Chester  group  in  Hardin  County,  the 
Degonia  has  furnished  very  few  fossils.  Those  that  have  been  observed  are 
fragmentary  plant  remains,  the  best  preserved  of  which  are  parts  of  Lepido- 
dendron  trunks. 


218  GEOLOGY  OF  HARDIN  COUNTY 

CORRELATION 

Of  all  the  Chester  formations  in  Illinois,  the  Degonia  sandstone  is  more 
nearly  traceable  from  the  typical  Eandolph  County  area  into  the  southern 
counties,  than  any  other.  It  has  been  recognized  in  the  Mississippi  River 
bluffs  southward  as  far  as  the  valley  of  Big  Muddy  River,  and  it  is  known  to 
be  well  developed  in  northern  Union  County.  When  the  small  intervening 
region  can  be  examined  in  detail,  it  is  altogether  probable  that  the  formation 
can  be  traced  continuously.  In  any  event  the  equivalency  of  the  sandstone 
from  Randolph  to  Hardin  County  cannot  be  questioned,  the  correlation  being 
based  not  alone  upon  its  continuity,  but  also  upon  the  uniformity  of  the 
paleontological   characteristics   of   the   underlying   and   overlying   limestones. 

Kinkaid  Limestone 
name  and  distribution 

During  the  past  season  (1919)  it  has  been  shown1  that  an  important 
limestone  is  present  in  the  Chester  section  of  Randolph  and  Jackson  counties, 
that  has  not  heretofore  been  recognized.  It  is  separated  from  the  Clore  lime- 
stone by  a  thick  and  massive  sandstone  formation,  the  Degonia  sandstone 
which  has  already  been  described.  The  formation  is  well  exposed  along  Kin- 
kaid Creek  and  some  of  its  tributaries  in  Jackson  County.  In  the  NW.  % 
sec.  6,  T.  8  S.,  R.  4  W.,  the  valley  of  this  creek  takes  the  form  of  a  gorge  cut 
through  the  limestone.  Because  of  these  exposures  the  name  Kinkaid  has 
been  chosen  to  designate  the  formation. 

This  limestone  is  known  to  be  present  in  Jackson  County  nearly  as  far 
south  as  Big  Muddy  River,  and  it  is  again  well  developed  in  northern  Union 
County.  Excellent  exposures  of  it  are  to  be  seen  entirely  across  Johnson  and 
Pope  counties,  and  it  continues  with  diminished  thickness  into  Hardin 
County.  South  of  Ohio  River  it  is  well  exposed  in  the  Chester  section  of 
Kentucky.  With  the  underlying  Degonia  sandstone  and  Clore  limestone,  the 
Kinkaid  is  not  present  in  the  southeastern,  unfanlted  portion  of  Hardin 
County,  the  pre-Pennsylvanian  unconformity  being  greater  in  this  part  of 
the  county  than  elsewhere,  in  consequence  of  which  the  Pottsville  sandstone 
rests  upon  the  Menard  limestone,  according  to  Butts. 

In  the  central  faulted  region  of  the  county  the  outcrops  of  these  three 
formations  are  essentially  restricted  to  the  deeply  down-dropped  middle  zone 
(see  figure  3),  and  in  all  of  the  fault  blocks  in  which  they  are  exposed,  except 
some  of  the  smaller  ones,  they  are  overlain  by  the  Pottsville  sandstone  which 
caps  all  of  the  higher  hills  along  this  belt.  In  most  of  the  northeastern  half 
of  this  belt  its  width  is  entirely  ocupied  by  the  Pottsville  beds,  but  from  an 
east-west  line  drawn  one  mile  north  of  the  line  between  townships  11  and  12 


Through  the  field  studies  of  Mr.  J.  Marvin  Weller. 


UPPER    MISSISSIPPI  AN    SERIES,    CHESTER    GROUP  219 

south,  the  Kinkaid  formation  is  exposed  beneath  the  Fottsville  along  both 
sides  of  the  fault  block.  Good  exposures  of  the  formation  are  exhibited  about 
Keelin  School,  and  for  a  distance  of  about  two  miles  northeast  of  this  school. 
Farther  north  the  Kinkaid  is  present  in  the  small  Chester  area  which  is  mostly 
confined  to  sec.  21,  T.  11  S.,  K.  9  E.,  on  the  northwestern  margin  of  the  same 
fault  block;  this  outcrop  occupies  a  belt  about  two  miles  long.  In  a  south- 
westerly direction  from  Keelin  School,  however,  there  is  an  interruption  in 
the  outcrops  of  the  Kinkaid  and  associated  formations,  but  beginning  at  Big 
Creek  they  are  again  well  exposed  more  or  less  continuously  beneath  the 
Fottsville,  to  the  Ohio  Eiver  bluffs  between  the  mouth  of  Wallace  Branch  and 
a  point  half  a  mile  east  of  the  mouth  of  Threemile  Creek. 

In  belt  number  one  of  the  central  faulted  zone,  these  formations  extend 
from  the  Wolrab  Mill  fault  just  south  of  Sparks  Hill,  eastwardly  to  the  Hog- 
thief  Creek  fault,  one-fourth  of  a  mile  north  of  Carrs  Store. 

In  the  northwestern  portion  of  the  county  the  Kinkaid  occupies  a  belt 
just  south  of  the  Pottsville  outcrops.  For  a  short  distance  between  Buzzards 
Point  and  High  Knob  this  belt  extends  northward  to  the  county  line  and 
beyond  into  Gallatin  County,  but  through  most  of  the  distance  there  is  an 
area  underlain  by  Pottsville  between  the  limestone  outcrops  and  the  county 
line.  East  of  the  Lee  fault  this  formation,  like  the  others,  is  offset  to  the 
southwest  and  then  continues  eastwardly  to  the  Wolrab  Mill  fault.  Northwest 
of  the  Herod  fault  which  crosses  the  extreme  northwestern  corner  of  Hardin 
County  there  is  a  small  area  of  limestone  which  is  in  fault  contact  with  the 
Pottsville  and  Kinkaid  on  the  southeast,  and  lies  in  normal  stratigraphic 
contact  with  the  Pottsville  on  the  north. 

LITHOLOGIC    CHARACTERS 

In  Hardin  County  the  Kinkaid  limestone  resembles  the  exposures  of  the 
same  formation  farther  west.  The  formation  is  in  the  main  limestone  and 
shale,  but  possibly  with  some  thin  minor  beds  of  sandstone.  The  limestone 
beds  are  rather  variable  in  character,  but  they  are  in  the  main  hard,  dense, 
and  compact,  breaking  with  a  splintery  or  conchoidal  fracture,  being  very 
similar  in  many  respects  to  the  limestones  of  the  Menard  formation.  In  color 
these  limestone  beds  are  gray,  yellowish,  or  black,  the  yellow  layers  being  a 
conspicuous  feature  in  many  outcrops.  The  yellow  color  is  rather  more 
common  in  the  Kinkaid  than  in  any  other  limestone  of  the  Chester  group. 
A  notable  difference  between  these  beds  and  those  of  the  Menard  is  in  the 
much  greater  amount  of  silica  which  they  include.  Some  of  the  limestone 
beds  themselves  are  apparently  siliceous,  and  in  addition  chert  beds  of  greater 
or  less  extent  are  scattered  through  the  formation.  One  especially  notable 
chert  bed  present  in  the  lower  part  of  the  formation,  seems  to  be  continuous 
through  Pope  and  Johnson  counties  at  least,  and  extends  into  the  adjoining 


220  GEOLOGY    OF    HARDIN    COUNTY 

part  of  Kentucky.  It  is  a  very  massive  chert  ledge  two  or  three  feet  in  thick- 
ness, whose  presence  is  commonly  indicated  by  the  great  amount  of  chert  in 
subcubical  masses,  varying  in  size  from  less  than  one  foot  to  as  much  as  two 
feet  or  more,  which  are  scattered  through  the  residuum;  locally  in  Pope 
County  this  massive  chert  ledge  is  well  exposed  in  situ.  It  is  commonly  light 
colored,  in  places  nearly  white,  elsewhere  with  a  greenish  tint.  Other  chert 
layers  are  present  in  the  formation,  most  of  them  being  dark  colored,  some 
bands  being  not  unlike  the  chocolate-colored  chert  layers  which  are  commonly 
present  in  the  Vienna  limestone  of  Pope  and  Johnson  counties.  Little  or  no 
chert  has  been  observed  in  the  formation  in  northern  Hardin  County,  and  it 
is  nowhere  so  conspicuous  as  in  many  localities  in  Pope  County. 

The  shales  of  the  Kinkaid  formation  are  fully  as  variable  in  character  as 
are  the  limestones.  In  color  they  are  black,  gray,  olive-green,  and  red,  one 
conspicuous  red  shale  bed  apparently  being  a  persistent  member  of  the  forma- 
tion. Some  of  the  shales  are  almost  pure  clay,  some  are  calcareous,  some  are 
siliceous,  and  some  are  more  or  less  sandy.  The  individual  beds  vary  in  thick- 
ness from  thin  shaly  partings  between  the  beds  of  limestone  to  strata  fifteen 
or  more  feet  in  thickness. 

THICKNESS 

The  exposures  of  the  Kinkaid  formation  in  Hardin  County  are  not  well 
adapted  for  determining  its  total  thickness.  In  those  situations  where  the 
basal  contact  of  the  formation  can  be  approximately  fixed,  the  superjacent 
Pottsville  is  not  present,  and  where  the  upper  limits  of  the  formation  can  be 
determined  the  base  is  not  well  exposed.  The  exposures  in  Pope  County  arc 
better  adapted  for  determining  the  thickness,  however,  and  from  field  studies 
made  in  that  county  it  has  been  determined  that  the  Kinkaid  exceeds  100  feet 
in  thickness  as  exhibited  in  surface  exposures.  As  indicated  by  deep  well 
records  it  seems  that  in  places  the  formation  is  even  thicker  than  this,  perhaps 
150  feet  or  more,  but  the  thickness  varies  because  of  the  extensive  post-Chester 
erosion  which  preceded  the  Pottsville  sedimentation.  Furthermore,  from 
the  fact  that  the  Pottsville  rests  upon  the  Menard  limestone  in  the  south- 
eastern portion  of  Hardin  County,  it  is  quite  likely  that  the  Kinkaid  forma- 
tion becomes  thinner  in  its  eastward  extension  from  Pope  County,  and 
disappears  entirely  before  the  eastern  border  of  Hardin  is  reached.  If  this 
condition  is  true  it  is  probable  that  nowhere  in  Hardin  County  does  the 
formation  attain  the  maximum  thickness  exhibited  farther  west,  and  it  prob- 
ably does  not  even  reach  the  thickness  shown  in  the  surface  outcrops  in  Pope 
County. 

STRATIGRAPIIIC    RELATIONS 

The  stratigraphic  relations  of  the  Kinkaid  formation  with  the  underly- 
ing Degonia  sandstone  have  already  been  considered  in  connection  with  the 


UPPER   MISSISSIPPIAN    SERIES,    CHESTER    GROUP  221 

description  of  the  older  formation.  No  evidence  is  at  hand  to  indicate  that 
a  stratigraphic  break  separates  the  two  formations.  The  upper  limit  of 
the  Kinkaid  limestone  is  everywhere  marked  by  the  sub-Pennsylvanian  uncon- 
formity that  is  present  throughout  the  entire  Illinois  basin.  The  actual  con- 
tact between  the  limestone  and  the  overlying  Pottsville  is  commonly  talus 
covered  and  has  been  observed  in  only  one  locality  near  Hardin  County.  This 
is  in  the  road  north  of  Karbers  Eidge  a  few  hundred  feet  north  of  the  county 
line.  Here  the  Kinkaid  is  immediately  overlain  by  a  ferruginous  con- 
glomerate, succeeded  above  by  sandy  shales  and  sandstones  as  shown  in  the 
following  section: 

Section  north  of  Karbers  Ridge 

Feet 

6.     Sandstone,   thin-bedded,   white 10 

5.     Shale,  fine,  fissile  clay,  with  iron  nodules 10 

4.     Shale   and   sandstone,   white   sandy   shale   and   white   sandstone   layers   of 

pure  white  quartz  sand  without  mica 10 

3.     Conglomerate,    ferruginous,    with    quartz    pebbles    up    to    one-half    inch    in 

diameter     1 

2.     Clay,  red  and  green,  and  limestone 15 

1.    Limestone,  buff  and  gray,  fine-grained iy2 

The  passage  here  from  the  Kinkaid  at  the  top  of  the  Mississippian  to 
the  Casey ville  formation  at  the  base  of  the  Pennsylvanian  is  abrupt  and  com- 
plete at  the  bottom  of  No.  3  of  the  above  section.  The  highly  ferruginous 
character  of  the  conglomerate  indicates  a  low,  swampy  condition  of  the  land 
for  a  long  time  before  and  during  the  gradual  transgression  of  the  Pennsyl- 
vanian conglomerate  upon  the  old  eroded  Mississippian  surface. 

In  one  section  in  Pope  County  the  base  of  the  Pottsville  is  marked  by  a 
conglomerate  which  includes  numerous  limestone  pebbles  and  small  boulders 
that  clearly  originated  from  some  of  the  underlying  Chester  formations,  and 
associated  with  them  are  red  granite  pebbles  which  vary  in  size  up  to  the 
magnitude  of  a  man's  fist,  which  must  have  been  transported  a  very  long 
distance. 

PALEONTOLOGY 

Most  of  the  limestone  beds  in  the  Kinkaid  formation  are  more  or  less 
fossiliferous,  but  the  fossils  are  not  generally  preserved  in  such  a  manner  as 
to  be  properly  identified.  The  shale  beds  of  the  formation  are  commonly  very 
little  if  at  all  calcareous,  and  are  likely  to  be  barren  of  fossils,  this  being 
especially  true  of  the  red  and  olive-green  shales.  From  one  layer  in  the  lime- 
stone in  the  NE.  %  SW.  %  sec.  30,  T.  12  S.,  E.  8  E.,  near  Threemile  Creek, 
two  miles  northwest  of  Eosiclare,  the  following  species  have  been  collected: 


222  GEOLOGY  OF  HARDIN  COUNTY 

Fossils  from  the  Kinkaid  limestone  collected  in  the  NE.  %  SW.  14  sec.  30,  T,  12  8., 
R.  8  E.,  northwest  of  Rosiclare 

Triplophyllum      spinulosum      (M.-E.         Spirifer  leidyi  N.  and  P. 

and  H.)  Martinia  contracta  M.  and  W. 

Orthotetes     kaskaskiensis  (McChes-         Eumetria  costata  (Hall) 

ney)  Cliothyridina  sublamellosa    (Hall) 

Productus  ovatus  Hall  Composita  trinuclea   (Hall) 

Productus  sp.       •  Bellerophon  sp. 

Diaphragmus  elegans   (N.  and  P.)             Naticopsis  sp. 

Camarophoria      explanata  (McChes-         Allorisma  sp. 

ney)  Aviculopecten  sp. 

Girtyella  sp.  Orthoceras  sp. 

This  fauna  has  nothing  strikingly  distinctive  about  it,  and  were  not  its 
horizon  definitely  fixed  by  its  stratigraphic  relations  it  might  be  considered  as 
of  middle  Chester  age.  The  examples  of  Composita  which  are  present  are  the 
the  C.  trinuclea  type,  identical  with  those  which  occur  commonly  in  the  middle 
and  lower  Chester  faunas,  and  not  at  all  like  the  large  and  broad  examples 
of  C.  subquadrata  of  the  Menard  and  Clore.  The  examples  of  Martinia  con- 
tracta most  resemble  those  which  have  been  collected  from  some  of  the  higher 
beds  of  the  Glen  Dean  formation  near  Golconda,  in  Pope  County. 

A  collection  from  the  outcrops  of  Kinkaid  limestone  on  Kinkaid  Creek 
in  Jackson  County,  exhibits  the  same  features  as  those  just  recorded  from 
Hardin  County.  A  species  of  Martinia,  apparently  the  same  as  that  in  the 
list  just  given,  is  one  of  the  common  forms,  and  the  Composita  present  is  of 
the  C.  trinuclea  type  rather  than  the  large  form  so  common  in  the  Menard 
and  Clore  limestones.  A  number  of  pelecypods  are  present  in  the  fauna, 
among  them  the  Menard  species  Sulcatopinna  missouriensis. 

CORRELATION 

The  only  question  of  correlation  involved  in  the  consideration  of  this 
limestone  in  Hardin  County,  is  its  equivalence  to  the  beds  in  Jackson  and 
Randolph  counties.  The  almost  complete  continuity  of  the  formation  from 
one  region  to  the  other,  with  the  common  paleontological  characteristics, 
sufficiently  establishes  the  identity  of  the  formation  entirely  across  southern 
Illinois. 


CHAPTEE  IX— PEXXSYLVAXIAX 

By  Chas.  Butts 

Sub-Pexnsylvaxiax  Unconformity 

The  Kinkaid  formation  of  the  Chester  group,  the  uppermost  of  the  Missis- 
sippian  formations  in  southern  Illinois,  is  succeeded  above  by  the  Caseyville 
formation,  the  lowest  formation  of  the  Pennsylvanian  system.  The  Kinkaid  is 
probably  not  the  youngest  formation  laid  down  in  Mississippi  an  time,  and 
the  Caseyville  certainly  is  not  the  oldest  formation  of  Pennsylvanian  time. 
Between  the  time  represented  by  the  top  of  the  Kinkaid  and  the  time  of  de- 
position of  the  basal  beds  of  the  Caseyville  in  Illinois,  there  was  formed  along 
the  eastern  margin  of  the  Appalachian  coal  fields,  a  great  series  of  rocks  that 
is  not  represented  in  Illinois,  but  which,  if  it  were  present,  would  lie  between 
the  Kinkaid  and  the  Caseyville.  These  beds  which  are  lacking  from  the  Illinois 
section  constitute  the  lower  part  of  the  coal-bearing  rocks  of  the  Anthracite 
fields  of  eastern  Pennsylvania,  the  rocks  of  the  Pocahontas  coal  field  of 
Virginia  and  West  Virginia,  and  the  Coal  Measures  of  Alabama,  the  aggre- 
gate maximum  thickness  of  which  is  probably  not  less  than  12,000  feet.  These 
lowest  Coal  Measures  rocks  which  are  not  represented  in  the  Illinois  section, 
are  classed  as  lower  and  middle  Pottsville.  The  oldest  Pottsville  rocks  of 
Illinois  are  of  middle  and  upper  Pottsville  age,  and  correspond  in  the  time  of 
their  origin  with  the  beds  which  overlie  the  lower  Pottsville  and  the  lower 
part  of  the  middle  Pottsville  rocks  of  the  Appalachian  coal  fields.  The  strati- 
graphic  relations  of  these  formations  are  shown  in  the  table  giving  the  general 
geologic  section  on  page  80,  and  by  the  accompanying  diagram,  fig.  13. 

In  a  conformable  geological  succession  one  layer  is  deposited  upon 
another  without  any  considerable  lapse  of  time  between  the  two  depositions, 
and  such  a  relation  doubtless  exists  between  some  of  the  formations  of  the 
Chester  group.  Between  the  deposition  of  the  Kinkaid  and  the  Caseyville 
formations,  however,  a  very  long  time,  perhaps  millions  of  years  intervened — 
all  the  time  in  fact  required  for  the  accumulation  of  the  thousands  of  feet 
of  rocks  including  many  thick  coal  beds,  that  are  present  in  the  Appalachian 
coal  fields  but  wanting  in  the  Illinois  section.  Just  what  was  taking  place 
in  Illinois  while  this  great  thickness  of  rocks  was  accumulating  farther  east, 
is  not  fully  known,  but  it  is  certain  that  the  region  was  land  during  that  time 
or  a  large  part  of  it.  Rocks  do  not  usually  accumulate  upon  a  land  surface. 
Instead  they  are  worn  away  from  it  and  carried  by  the  streams  to  the  ocean 

223 


224 


GEOLOGY  OF  HARDIN  COUNTY 


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PENNSYLVANIAN  225 

or  some  other  body  of  water  where  the  transported  material  is  deposited  upon 
the  bottom  to  form  new  rock  strata.  Much  might  he  written  upon  this  sub- 
ject of  unconformity  but  enough  has  probably  been  said  to  give  the  reader  an 
understanding  of  what  is  meant  by  the  statement  that  a  great  unconformity 
exists  between  the  Kinkaid  and  the  Caseyville  formations. 

Pottsville  Group 

The  Pennsylvanian  system,  commonly  called  the  "Coal  Measures"  by 
earlier  geologists,  takes  its  name  from  the  state  of  Pennsylvania,  where  the 
coal  bearing  rocks  are  typically  developed,  and  where  they  first  became  well 
known  in  America  through  coal  mining  operations.  The  most  distinctive 
feature  of  the  Pennsylvanian  system  in  eastern  North  America  is  its  coal 
beds.  The  Pennsylvanian  system  in  Hardin  County  includes  only  the  lowest 
rocks  .  of  the  Illinois  "Coal  Measures."  The  strata  include  conglomerate, 
sandstone,  shale  and  thin  coal  beds,  and  they  belong  in  the  middle  and  upper 
divisions  of  the  Pottsville  group,  a  series  of  formations  that  has  its  typical 
development  in  Pennsylvania,  and  which  have  been  named  from  the  city  of 
Pottsville  in  that  state.  In  Hardin  County  two  formations  of  Pottsville  age 
are  recognized,  the  Caseyville  below  and  the  Tradewater  above.  As  stated  in 
the  preceding  pages  and  shown  on  Table  I  the  lower  Pottsville  rocks,  many 
thousands  of  feet  thick,  in  the  southern  Appalachian  coal  fields  of  West 
Virginia  and  Alabama,  are  not  definitely  known  to  be  represented  in  Illinois. 

Caseyville  Formation 

NAME  AND  DISTRIBUTION 

The  Caseyville1  formation  has  been  named  from  Caseyville,  Kentucky,  a 
town  located  upon  the  formation  lying  just  across  Ohio  Eiver  from  Battery 
Eock  in  Hardin  County.  The  Caseyville  formation  occupies  a  large  area  in 
Hardin  County  bordering  the  river  in  Battery  Rock  and  Eock  Creek  town- 
ships; a  large  area  extending  southwest  from  Zion  Church  to  Keelin  School 
and  lying  between  the  Hogthief  Creek  and  Peters  Creek  faults;  a  strip  of 
varying  width  along  the  north  side  of  the  county;  and  several  isolated  tracts 
in  the  southwestern  part  of  the  county  of  which  Stone  Hill  and  the  hill  lying 
between  Threemile  Creek  and  Wallace  Branch  are  the  most  important.  The 
formation  extends  also  into  the  part  of  Pope  County  shown  on  the  map, 
Plate  I. 

LITHOLOGIC  CHARACTERS 

The  Caseyville  formation  is  composed  of  conglomerate,  sandstone,  and 
shale,  as  is  shown  in  the  generalized  columnar  section   (PL  I).     There  is  at 

1  Glenn,  L.  C,  Coal  of  the  Tradewater  River  Region;  Ky.  Geol.  Surv.,  Bull.  17,   (1912). 
—15  G 


226  GEOLOGY    OF    HARDIN    COUNTY 

the  bottom  of  the  formation  in  Battery  Rock  and  Rock  Creek  townships,  a 
sandstone  40  feet  thick,  locally  containing  layers  with  rather  abundant  small 
quartz  pebbles,  that  may  be  called  conglomerate.  This  sandstone  yields  some 
large  masses  20  feet  or  so  in  thickness  along  the  base  of  the  river  bluff  in 
sec.  2,  T.  12  S.,  R.  10  E.  It  also  forms  the  low  basal  cliff  high  up  on  the 
points  of  the  spurs  or  near  the  brows  of  the  hillsides  northeast  of  Honey  Creek 
valley  between  Lamb  and  Zion  Church,  where  the  member  rests  upon  the 
Menard  limestone  of  the  Mississippian.  Elsewhere  in  the  county  this  bed 
seems  to  be  wanting  from  the  Caseyville  section.  Overlying  the  basal  sand- 
stone member  or  resting  upon  the  Chester  limestone  where  this  member  is  not 
present,  there  are  about  100  feet  of  interbedded  sandstone  and  shale,  suc- 
ceeding which  is  a  second  sandstone  and  conglomerate  member  60  feet  thick. 
This  member  is  thick-bedded  and  mostly  coarse  and  friable  in  texture,  with 
quartz  pebbles  up  to  one-half  inch  in  diameter  scattered  about  locally  or  in 
irregular  nests  and  pockets.  It  is  the  massive  cliff-making  sandstone  at 
Battery  Rock  landing,  and  is  the  basal  sandstone  along  the  northern  border 
of  the  county  and  in  the  cliffs  to  the  northeast  of  Peters  Creek  in  the  NE.  14 
sec.  33,  the  NW.  %  sec.  34,  and  the  SW.  %  sec.  27,  T.  12  S.,  R.  9  E.,  and  it  is 
probably  this  member  that  caps  the  hills  which  constitute  the  separated  areas 
of  Pottsville  rocks  in  the  southwestern  part  of  the  county.  Above  the  second 
sandstone  and  conglomerate  member  is  about  100  feet  of  thin  sandstone  and 
shale  including,  near  the  top,  the  Battery  Rock  coal  bed,  which  is  known  only 
on  the  knob  near  and  slightly  north  of  west  of  Battery  Rock.  Succeeding  the 
second  mass  of  shale  and  sandstone  is  the  third  conglomerate  and  sandstone 
member  of  the  Caseyville,  over  100  feet  thick,  forming  the  top  of  the  forma- 
tion. This  uppermost  member  is  similar  in  lithologic  character  to  the  two 
lower  sandstone  and  conglomerate  members;  it  forms  the  high  cliffs  near 
Sellers  Landing,  and  also  those  at  the  mouth  of  Cane  Creek  and  along  Blind 
Hollow,  below  the  mouth  of  Saline  River.  Along  the  northern  boundary  of 
the  county  the  same  bed  forms  the  high  cliffs  at  The  Pounds  in  southern 
Gallatin  County,  and  continues  westward  along  the  county  line  where  it  caps 
High  Knob  just  north  of  the  county  line  one  and  one-half  miles  north  of 
Karbers  Ridge,  and  forms  the  cliff  at  Buzzards  Point,  and  the  very  con- 
spicuous upper  cliffs  in  sec.  2,  T.  12  S.,  R.  7  E. 

BATTERY  ROCK    COAL 

The  Battery  Rock  coal,  near  Battery  Rock,  is  the  only  workable  coal  bed 
known  in  the  Caseyville  formation  in  Hardin  County.  It  is  about  20  feet 
below  the  base  of  the  upper,  massive  sandstone  member  of  the  formation. 
Only  a  few  acres  were  originally  underlain  by  the  coal,  namely  those  com- 
prising the  top  of  the  knob  a  third  of  a  mile  slightly  northwest  of  the  old 
Battery  Rock  landing,  in  the  center  of  the  west  side  of  sec.  26,  T.  12  S.,  R.  10 
E.,  where  it  formerly  was  mined  and  is  reported  to  have  been  26  inches  thick. 


PENNSYLVANIAN  227 

The  available  coal  at  this  locality  seems  to  have  been  nearly  or  completely 
worked  out. 

THICKNESS 

The  entire  thickness  of  the  Casey ville  is  probably  about  400  feet,  divided 
between  the  various  members  as  stated  in  the  foregoing  description.  Because 
the  full  thickness  of  the  formation  is  not  present  and  accessible  at  any  one 
locality,  it  is  impossible  to  make  a  direct  measurement  of  it,  and  the  thickness 
as  given  has  to  be  compiled  from  measurements  made  of  different  members  at 
different  points,  with  a  consequent  possibility  of  considerable  error. 

Paleontology 
A  good  collection  of  fossil  ferns  has  been  obtained  from  the  Caseyville 
formation  on  the  west  side  of  Stone  Hill  in  the  SW.  %  sec.  17,  T.  12  8.,  R.  8 
E.  The  plants  occur  in  a  dark,  sandy  shale  that  apparently  underlies  the 
middle  conglomerate  of  the  complete  Caseyville  section.  At  this  place  the 
lowest  conglomerate  is  believed  to  be  absent,  and  the  plant-bearing  shale  is  not 
a  great  distance  above  the  top  of  the  Kinkaid  limestone  of  the  Chester.  The 
species  of  the  ferns,  as  they  have  been  identified  by  David  White,  are  listed 
below  : 

Fossil  ferns  from  the  Caseyville  formation  collected  on  Stone  Hill  in  the  SW.  *4 

sec.  17,  T.  12  &.,  R.  8  E. 

Alethopteris   decurrens    (Artis)  Cheilanthites  cf.  macilenta 

Alethopteris   grandifolia  Newb.  Megalopteris   sp.  ? 

Alethopteris  lonchitica  (Schl.)    (Ohio  Neuropteris  cf.  obliqua 

form)  Sphenopteris  communis  Lesq. 

Cardiocarpon  sp.  ?  Whittleseya  microphylla  Lesq. 

CORRELATION 

According  to  White  the  species  of  ferns  recorded  in  the  foregoing  list, 
indicate  a  horizon  probably  near  that  of  the  Sharon  conglomerate  which  is 
the  basal  member  of  the  Upper  Pottsville  of  western  Pennsylvania.  It  is 
possible,  however,  that  the  flora  may  fall  in  the  upper  part  of  the  Middle 
Pottsville.  The  beds  containing  this  flora  are  probably  of  Morrow  age.  The 
oldest  floras  from  the  Pottsville  in  Illinois  are  of  Middle  Pottsville  age  with 
a  possibility  that  the  lowest  flora,  as  yet  but  little  seen,  may  be  of  Lower 
Pottsville  age.  The  lowest  plant  horizon  noted  on  Battery  Pock  is  of  Middle 
Pottsville  age.  The  Caseyville  includes  beds  older  than  the  lowest  of  the 
Missouri  Coal  Measures,  which  probably  correspond  more  closely  to  the  Trade- 
water  formation  which  immediately  overlies  the  Caseyville  in  Hardin  County. 

In  the  Caseyville  of  Pope  County,  coal  is  known  to  exist  in  two  localities. 
The  one  of  these  visited  by  the  writer  is  in  a  ravine  in  the  SW.  %  NE.  % 
sec.  6,  T.  11  S.,  R.  7  E.  Here  the  coal  has  been  mined  and  a  face  of  about 
2y2  feet  of  clean  coal  was  exposed  m  the  midst  of  massive  sandstone.    Another 


228  GEOLOGY  OF  HARDIN  COUNTY 

place  where  coal  is  reported  to  have  been  mined  for  use  at  the  Empire  fluorspar 
mine,  appears  to  be  located  as  well  as  the  writer  could  make  out  from  descrip- 
tions, in  the  SE.  %  S.W.  %  sec.  16,  T.  11  S.,  R.  7  E.  This  place  was  not 
visited.  It  is  not  improbable  that  the  coal  bed,  which  is  well  up  in  the  Casey- 
ville  at  both  places,  is  the  same  as  the  Battery  Rock  coal. 

TRADEWATER  FORMATION 
NAME  AND  DISTRIBUTION 

The  Tradewater  formation  was  named  by  Glenn1  from  Tradewater  River 
in  Kentucky,  east  of  Casey ville,  along  which  stream  it  has  a  good  width  of 
outcrop.  It  includes  all  the  beds  between  the  top  of  the  upper  conglomerate 
of  the  Caseyville,  and  the  Davis  coal,  No.  6  of  the  Kentucky  section,  which 
is  the  equivalent  of  the  Murphysboro  or  No.  2  coal  of  Illinois.  The  forma- 
tion occupies  but  a  small  area  in  Hardin  County  and  is  confined  to  its 
northeastern  part,  lying  in  a  narrow  strip  south  of  Saline  River  and  south  of 
the  north  line  of  the  county  to  a  point  as  far  west  as  Sparks  Hill.  The  areas 
in  the  vicinity  of  Mount  Zion  Church  and  Baugher  School  are  offset  to  the 
southwestward  from  the  belt  south  of  Saline  River,  in  the  deeply  downthrown 
fault  block  between  the  Peters  Creek  and  Hogthief  Creek  faults.  The  full 
thickness  of  the  formation  probably  is  not  present  in  the  county,  for  the 
Carbondale  formation,  next  overlying  the  Tradewater  in  the  Illinois  section, 
is  not  known  to  occur  here. 

LITHOLOGIC  CHARACTERS 

The  Tradewater  formation  is  composed  almost  entirely  of  shale  and 
sandstone,  but  associated  with  these  strata  are  two  thin  coal  beds  and  a  single 
layer  of  yellow  limestone  six  inches  thick.  The  shale  is  gray  and  somewhat 
sandy  and  micaceous.  Much  of  the  sandstone  is  thick  to  massive-bedded, 
coarse,  friable,  and  feldspathic. 

COAL  BEDS 

In. the  ravine  just  back  of  the  store  at  Saline  Landing,  a  coal  bed  about 
twenty  inches  thick  lies  apparently  some  50  feet  above  the  bottom  of  the 
Tradewater  formation,  and  is  supposed  to  be  the  Bell  coal  of  the  Kentucky 
section.  On  the  steep  bank  just  above  the  private  road  in  the  SW.  %  sec-  *> 
T.  11  S.,  R.  9  E.,  there  is  a  higher  coal  bed,  apparently  over  two  feet  thick, 
which  dips  strongly  to  the  northwest  so  as  to  lie  below  the  Saline  River  flats, 
immediately  to  the  northeast  of  the  road.  The  yellow  limestone  layer  which 
has  been  mentioned,  lies  just  above  this  coal.  In  the  Tradewater  of  the 
mapped  area  in  Pope  County,  a  coal  about  18  inches  thick  outcrops  in  the 
road  half  a  mile  north  of  Harts  Store.    Below  it  is  a  siliceous  limestone  with 


1  Glenn,  L.  C,  Coal  of  the  Tradewater  River  Region;  Ky.  deol.  Surv.,  Bull.  17,  (1912). 


PENNSYLVANIA^  229 

invertebrate  fossils  including  Marginifera  muricata  and  Chonetes  mesolobus. 
This  is  probably  the  Curlew  limestone  and  the  coal,  the  Curlew  coal. 

THICKNESS 

The  thickness  of  that  portion  of  the  Tradewater  represented  in  Hardin 
County  is  estimated  as  300  feet.  The  greatest  thickness  seems  to  be  under  the 
high  knob  a  third  of  a  mile  north  of  Lambert  School  in  sec.  3,  T.  11  S.,  E. 
9  E.  If  the  beds  were  horizontal  at  this  point  there  would  be  at  least  220 
feet  of  Tradewater  represented,  but  allowing  for  increased  thickness  due  to  a 
north  dip  of  5°  to  10°  the  thickness  must  be  not  less  than  300  feet.  In  Pope 
County  the  thickness  probably  reaches  about  500  feet.  The  full  thickness  of 
the  formation  in  Kentucky  is  given  as  594  feet.1 

PALEONTOLOGY  AND  CORRELATION 

The  fossils  of  the  Tradewater  formation  are  of  Upper  Pottsville  age, 
specifically  of  Mercer,  and  probably  of  Conoquenessing  age.  On  combined 
stratigraphic  and  paleontologic  evidence  it  is  concluded  that  the  Tradewater 
is  of  Upper  Pottsville  age,  and  probably  includes  beds  of  the  same  age  as  the 
Homewood  sandstone  and  Mercer  shale  of  western  Pennsylvania. 

1  Lee,  Wallace,  Geology  of  the  Shawneetown  quadrangle  in  Kentucky  :    Ky.  Geol.  Surv. 
(1916). 


CHAPTER  X— SURFICIAL  DEPOSITS 

By  Stuart  Weller 

General  Statement 

The  hard  rocks  which  underlie  the  whole  of  Hardin  County  are  hidden 
from  view  over  most  of  the  area  by  unconsolidated  materials  which  constitute 
the  so-called  mantle  rock  or  surficial  deposits.  This  material  has  had  a  very 
different  origin  from  that  of  the  hard  rocks,  all  of  which  were  accumulated 
in  the  waters  of  the  ocean.  These  mantle  rocks  are  all  terrestrial  deposits, 
that  is  they  were  accumulated  upon  the  surface  of  the  dry  land,  although  it 
is  understood  that  some  of  the  material  was  actually  accumulated  through 
the  agency  of  the  fresh  waters  of  Ohio  Eiver  and  its  tributary  streams.  The 
surficial  deposits  in  Hardin  County  are  of  three  sorts,  the  residual  deposits, 
the  alluvial  deposits,  and  the  wind-blown  deposits. 

Residual  Detosits 

The  residual  deposits  include  all  of  those  which  have  accumulated  in 
place,  by  the  disintegration  or  weathering  of  the  hard  rocks.  An  important 
type  of  such  deposits  is  the  red  clay  beds  which  overlie  the  limestone  forma- 
tions throughout  the  county,  wherever  such  material  has  not  been  washed 
away  by  the  waters  that  have  fallen  as  rain  and  have  been  drained  off  through 
the  streams.  These  residual  clay  deposits  are  made  up  of  the  insoluble  ma- 
terial that  is  left  behind  where  the  limestone  has  been  removed  by  solution, 
and  imbedded  in  the  clay  are  any  insoluble  portions  of  the  limestone,  such  as 
the  siliceous  beds  which  we  call  chert  or  flint.  Because  some  of  the  limestones 
of  the  county  are  very  cherty,  some  of  the  clays  of  this  sort  are  filled  with 
broken  fragments  of  chert  which  were  originally  in  the  form  of  flint  or  chert 
layers  in  the  solid  limestone,  such  as  are  seen  in  the  Ohio  River  bluffs  at 
Elizabethtown. 

Some  of  the  residual  deposits  may  have  been  moved  short  distances  in 
the  process  of  their  accumulation.  Such  would  include  the  talus  deposits 
which  accumulate  along  the  bases  of  bluffs  or  steep  hills.  These  deposits  are 
made  up  of  masses  of  rock  of  greater  or  less  size  which  have  been  broken  off 
from  the  outcropping  ledges  in  the  upper  part  of  the  hills  through  the  action 
of  frost,  by  the  pressure  of  the  growing  roots  of  plants  and  trees,  by  the  un- 
dermining of  an  upper,  more  insoluble  formation  like  sandstone,  by  the 
solution  or  disintegration  of  an  underlying  limestone  or  shale,  or  by  the  slow 

231 


232  GEOLOGY    OF    HARDIN    COUNTY 

disintegration  of  the  rocks.  Material  of  this  sort  rolls  down  the  hill  side 
and  accumulates  at  its  base  mixed  with  soil.  The  size  of  the  rock  fragments 
in  the  talus  may  vary  in  size  from  small  particles  to  masses  of  many  cubic 
yards. 

Alluvial  Deposits 

A  second  type  of  surficial  material  is  that  which  has  accumulated  in  the 
stream  valleys  through  the  agency  of  the  transportive  power  of  the  streams. 
'The  source  of  the  material  is  the  residuum  which  has  accumulated  as  already 
described,  either  here  in  Hardin  County  or  elsewhere.  This  material  is  con- 
stantly being  carried  down  grade  by  the  movement  of  water  which  falls  as 
rain,  and  will  eventually  be  transported  to  the  ocean,  but  as  the  streams  have 
cut  down  their  valleys,  level  stretches  have  been  formed  in  some  places,  in 
which  the  slacking  of  the  current  has  caused  the  material  being  carried  to 
be  dropped.  Such  accumulations  of  material  make  up  in  part  the  alluvial 
deposits  of  the  so-called  bottom  lands.  In  some  of  the  stream  valleys  of  the 
county,  such  as  Big  Creek,  whose  bottom  lands  are  subject  to  overflow  from 
backwater  of  Ohio  Eiver,  these  alluvial  deposits  are  added  to  from  year  to 
year  by  the  settling  of  part  of  the  fine  sediment  held  in  suspension  by  the 
overflow  waters. 

There  are  really  three  types  of  alluvial  deposits  in  the  county;  the  ma- 
terial accumulating  in  the  narrow  bottom  lands  of  some  of  the  streams 
tributary  to  Ohio  Eiver;  that  accumulating  in  the  Ohio  River  valley  itself 
at  the  present  time ;  and  material  which  has  accumulated  in  the  Ohio  Eiver 
Valley  at  an  earlier  period  when  the  river  level  itself  was  higher  than  it 

now  is. 

Geologically  speaking  all  alluvial  deposits  are  only  temporary,  and  if  the 
full  cycle  of  erosion  is  completed  they  will  finally  be  deposited  in  the  ocean; 
but  humanly  speaking,  some  of  these  deposits  remain  in  position  for  thou- 
sands of  years.  If  there  is  any  way  of  determining  the  length  of  time  that 
an  alluvial  deposit  in  a  stream  valley  remains  undisturbed,  definite  evidence 
becomes  available  which  establishes  within  certain  definite  limits  the  age  of 
the  valley  itself  where  the  deposit  occurs,  and  consequently  some  idea  can  be 
gained  of  the  length  of  time  during  which  the  present  topography  of  the 
region  has  remained  comparatively  unchanged.  The  most  satisfactory  sort 
of  evidence  to  establish  such  facts  as  these  is  paleontological,  that  is,  the 
evidence  afforded  by  the  remains  of  animals  or  plants  which  have  existed  in 
the  past.  Fortunately,  in  Hardin  County,  evidence  of  this  sort  is  available, 
for  there  has  been  found  buried  in  the  alluvial  deposits  in  the  valley  of  Big 
Creek,  about  three  and  one-half  miles  from  the  stream's  mouth,  the  skeleton 
of  a  mastodon,  an  animal  related  to  the  living  elephant,  which  formerly  lived 
throughout  the  interior  of  North  America,  but  which  has  long  been  extinct. 
While  of  course  it  is  not  possible  to  determine  the  exact  number  of  years  that 


SURFICTAL   DEPOSITS  233 

have  elapsed  since  the  mastodan  was  living  in  southern  Illinois  or  elsewhere, 
the  evidence  which  has  been  accumulated  throughout  the  country,  goes  to 
show  that  these  creatures  have  been  extinct  for  ten  thousand  years  or  more, 
and  consequently  it  can  be  concluded  that  the  valley  of  Big  Creek  has  existed 
in  essentially  its  present  condition  for  that  length  of  time.  This  evidence 
from  Big  Creek  carries  with  it  the  assumption  that  the  present  topography  of 
Hardin  County  has  existed  with  but  comparatively  little  change  for  at  least 
ten  thousand  years,  and  perhaps  considerably  longer,  and  while  this  is  a  long 
time  in  human  experience,  it  is  a  very  brief  period  in  geology. 

The  alluvial  deposits  of  the  Ohio  Eiver  bottom  were  accumulated  in  the 
same  manner  as  those  of  the  smaller  streams,  but  the  source  of  the  material 
was  not  local,  much  of  it  having  been  carried  down  the  stream  from  far  to 
the  east,  perhaps  as  far  away  as  Pennsylvania.  With  every  overflow  of  the 
river  a  thin  layer  of  sediment  is  deposited  in  places  on  its  flood  plain,  while 
elsewhere  material  may  be  carried  away.  On  the  whole,  doubtless,  the  flood 
plain  is  being  very  slowly  built  up  by  the  addition  of  such  sedimentary 
material. 

If  the  mouth  of  Ohio  Eiver  should  be  lowered  in  any  manner,  the  channel 
would  be  quickly  cut  down  to  a  position  to  conform  with  the  new  elevation 
of  the  mouth,  in  which  case  the  present  flood  plain  would  be  left  relatively 
high  above  the  river  level  and  would  not  be  subject  to  overflow,  and  a  new 
flood  plain  would  be  built  at  a  lower  elevation,  the  remnants  of  the  present 
one  being  left  as  a  terrace.  The  plain  upon  which  the  lower  portion  of  the 
town  of  Bosiclare  is  built  is  a  terrace  produced  in  a  comparable  manner,  and 
a  few  other  remnants  of  the  same  terrace  are  recognizable  elsewhere  in  the 
county. 

Wind  Blown  Deposits 

The  uplands  of  Hardin  County,  and  the  hill-sides  with  more  gentle 
slopes,  are  covered  with  an  exceedingly  fine,  yellowish  or  reddish-yellow  ma- 
terial which  characteristically  constitutes  all  of  the  upland  soil  of  the  county. 
This  material  was  not  derived  from  the  underlying  hard  rocks,  for  its  char- 
acter is  the  same  whether  it  overlies  limestones  or  sandstones.  It  could  not 
have  been  carried  to  its  present  position  through  the  action  of  running  water, 
for  it  has  its  best  development  and  is  purest  in  character  on  the  tops  of  the 
hills.  The  wind  is  the  only  agent  that  could  have  placed  it  where  it  now  is, 
and  because  of  its  exceedingly  fine  texture  it  might  easily  have  been  trans- 
ported in  that  manner.  It  is  known  that  in  an  earlier  period  in  the  history 
of  the  region  the  broad  Ohio  Eiver  flood-plain  was  essentially  bare  of  vegeta- 
tion, and  in  consequence  during  that  period  an  abundance  of  material  was 
available  in  the  fine  river  silts  of  the  flood  plain,  which  could  be  picked  up 
by  the  winds  blowing  from  the  south  and  be  carried  up  onto  the  hills.  In 
order  to  be  convinced  of  the  efficacy  of  the  wind  to  accomplish  this  sort  of 


234  GEOLOGY  OF  HARDIN  COUNTY 

work  it  is  only  necessary  to  watch  one  of  the  sand  bars  of  the  present  river 
in  a  low  stage  of  the  water,  during  a  brisk  wind,  when  clouds  of  material  are 
raised  into  the  air.  At  a  time  when  the  whole  flood-plain  of  the  stream  from 
valley  wall  to  valley  wall  was  bare  of  vegetation,  one  can  imagine  the  great 
quantity  of  material  which,  during  a  large  portion  of  the  year,  could  be 
transported  in  this  manner.  As  the  vegetation  gradually  came  to  clothe  the 
surface,  the  wind  could  no  longer  pick  up  such  vast  quantities  of  material, 
and  the  hills  themselves  gradually  became  covered  with  trees  and  other  forms 
of  vegetation. 

Since  the  period  of  its  original  deposition  much  of  this  wind-blown 
material  which  is  commonly  called  loess,  has  been  shifted  more  or  less  by 
slumping  and  by  wash,  so  that  in  many  places  it  has  now  become  more  or  less 
mingled  with  the  underlying  residuum  upon  which  it  was  originally  deposited, 
but  it  still  remains  in  its  pure  condition  upon  most  of  the  hill  tops.  It  is  this 
loess  that  is  so  easily  gullied  by  the  run  off  of  the  rain  water,  and  upon  many 
slopes  that  have  been  cultivated  for  a  considerable  period  of  time,  excellent 
exposures  of  the  formation  can  be  seen  in  the  gullies  that  have  been  formed. 
Not  infrequently  the  strong  contrast  in  character  between  the  upper  mantle 
of  loess,  and  the  underlying  residuum  of  clay  and  chert,  which  does  not  wash 
so  easily,  can  be  seen. 


PART  IV 
IGNEOUS  ROCKS 

By  L.  W.  Currier 


CHAPTER  XI.     IGNEOUS  ROCKS 

By   L.  W.  Currier 

The  igneous  rocks  of  Hardin  County  are  of  three  types:  (1)  fine- 
grained, dark-colored  trap  or,  more  technically,  lamprophyre,  (2)  medium- 
grained,  dark-colored  mica-peridotite,  and  (3)  volcanic  breccia (?).  All 
three  types  are  severely  altered,  so  that  a  close  classificaton  cannot  be  made. 
The  lamprophyre  occurs  as  narrow  dikes  and  sheets  enclosed  in  the  sediments ; 
the  peridotite  is  found  only  in  the  form  of  dikes ;  and  the  volcanic  breccia  is 
seen  as  weathered  boulders  suggesting  by  their  distribution  an  elliptical  in- 
trusion of  volcanic  rock.  The  exposures  of  igneous  rocks  thus  far  identified 
are  mainly  along  the  bluffs  of  Ohio  River,  where  the  prominent  and  freshly 
eroded  cliffs  of  sedimentary  rocks  render  the  igneous  intrusions  fairly  con- 
spicuous. North  of  the  river  only  a  few  scattered  outcrops  have  been  identi- 
fied, but  this  does  not  necessarily  indicate  an  occurrence  limited  to  the 
outcrops  since  the  igneous  material  decays  readily  and  becomes  obscured  by 
the  soil  which  covers  most  of  the  upland.  Because  of  these  conditions,  igneous 
activity  of  greater  intensity  is  to  be  inferred  than  the  few  occurrences  of 
igneous  rocks  mapped  would  alone  indicate. 

The  lamprophyre  and  mira-peridotite  have  been  described1  by  Johannsen 
and  thin  sections  have  also  been  examined  by  the  writer.  The  lamprophyre 
is,  in  general,  composed  of  conspicuous  sheets  of  phlogopite,  small  crystals  of 
pyroxene  partly  altered  to  serpentine,  and  fresh  prisms  of  apatite,  in  a  dense 
ground  mass  almost  wholly  altered  to  calcite  but  still  preserving  the  rem- 
nants of  a  pattern  suggesting  the  former  presence  of  feldspar  laths.  The 
mica-peridotite  is  made  up  of  olivine  and  pyroxene  crystals,  either  partly  or 
largely  altered  to  serpentine,  together  with  phlogopite,  iron  oxides,  and 
obscure  alteration  products.  The  volcanic  breccia  is  composed  of  angular  to 
rounded  pieces  of  both  igneous  material  and  sediments,  together  with  frag- 
ments of  feldspar,  grains  of  quartz,  and  much  alteration  material. 

The  separate  occurrences  will  be  briefly  described,  with  particular  refer- 
ence to  those  features  which  may  have  a  bearing  on  the  question  of  ore 
genesis. 

Orrs  Landing  Dike.— At  Orrs  Landing  (NE.  %  sec.  33,  T.  12  S.,  R.  8 
E.),  a  small  dike  cuts  Fredonia  limestone  in  a  N.  28°  W.  direction,  with  a  dip 
J  of  85°  NE.  (fig.  14).  The  dike  is  12  to  15  inches  wide.  The  wall-rock  is 
affected  to  a  distance  of  one-half  inch  by  recrystallization. 


1  Bain,   H.   Foster,    The   fluorspar   deposits   of  southern    Illinois:      U.    S.    Geol.    Survey 
Bull.  255,  pp.   28-30,  1905. 

237 


238 


GEOLOGY  OF  HARDIN  COUNTY 


The  dike  contains  many  rounded,  flattened,  and  angular  pieces  of  lime- 
stone and  quartzitic  sandstone  probably  representing  fragments  of  the  under- 
lying sediments  caught  in  the  fluid  magma  and  incorporated  in  the  intrusive 
rock. 

Megascopically,  the  dike  material  is  dark  gray  in  color,  and  porphyritic 
in  texture,  with  a  dense  grounclmass.  The  phenocrysts  are  of  dark  mica.  No 
other  minerals  may  be  distinctly  recognized,  and  the  rock  shows  by  its  color, 
hardness,  and  porosity,  the  extreme  alteration  which  it  has  suffered. 

Under  the  microscope,  the  rock  is  seen  to  be  largely  altered  to  calcite, 
among  the  crystals  of  which  may  be  recognized  remnants  of  augite,  grains  of 
magnetite,  and  prisms  of  apatite.     The  latter  mineral  appears  in  prominent 


Fig.  14. — Peridotite  dike,  with  pebbles  of  different  kinds  of  rock  and  calcspar, 
in  Ste.  Genevieve  limestone.  At  Orrs  Landing  on  Ohio  River  about  2  miles  south- 
west of  Elizabethtown. 


amount.  There  are  no  feldspar  grains  to  be  seen,  which  may  be  due  to  the 
extreme  weathering  of  the  whole  mass.  Probably  some  of  the  calcite  and 
other  alteration  products  were  derived  from  feldspar  grains.  On  account  of 
the  great  uncertainty  regarding  the  original  constituents,  the  rock  is  given 
the  general  name  of  lamprophyre. 

The  dike  is  partly  bordered  and  traversed  by  narrow  veinlets  of  crystal- 
line calcite  carrying  a  conspicuous  quantity  of  flaky  hydrocarbon  material, 
grains  of  galena  and  sphalerite,  scattered  plates  of  barite,  and  radiating 
clusters  of  aragonite  fibers.  Both  fluorspar  and  barite  are  also  found  lying 
between  the  dike  and  calcite  seam,  where  the  latter  branches  into  the  wall 


IGNEOUS   ROCKS 


239 


rock,  and  these  two  minerals  in  places  cut  across  the  dike.  This  mineral 
association  is  the  same  as  that  characteristic  of  the  fluorspar  veins,  a  fact 
which  seems  to  signify  a  close  connection  between  the  intrusion  of  the  dike 
material  and  the  period  of  mineralization. 

Rosiclcare  Dikes. — In  the  second  quarry  in  the  river  bluffs  east  of  Eosi- 
clare,  two  dikes,  8  to  10  inches  in  width,  cut  the  Fredonia  limestone.  These 
dikes  are  about  10  feet  apart  and  trend  N.  40°  W.  with  a  dip  of  80°  NE. 
The  limestone  walls  show  no  alteration.  Parallel  with  the  dikes  are  veins  of 
calcite,  up  to  15  inches  in  width,  composed  of  a  very  coarse  calcite  similar  to 
that  found  in  the  large  fluorspar  veins. 

The  material  of  both  dikes  is  largely  altered  to  calcite  and  chlorite ;  large 
plates  of  the  latter  are  the  most  prominent  megascopic  feature.  Johannsen's 
microscopical  description1  states  that  the  rock  is  "almost  entirely  altered  to 
calcite."  He  reports  the  presence  of  large  apatite  crystals,  iron  oxide, 
chlorite,  and  serpentine. 


Fig.  15. — Block  of  Renault  limestone  injected  by  a  peridotite  sill  (black 
layers)  parallel  to  the  bedding  planes.  Injected  layer  about  4  feet  thick.  At 
Downeys  bluff,  north  knob,  just  south  of  Rosiclare. 

Downey s  Bluff  Sill  and  Dike. — Near  the  top  of  the  eastern  peak  of  the 
high  bluff  between  Fairview  and  Eosiclare  landings,  a  sill  occurs  in  the  beds 
of  the  Eenault  limestone  (fig.  15).  In  places  it  attains  a  thickness  of  2% 
feet,  but  elsewhere  divides  into  narrower  sheets  which  cross  the  limestone  beds 
in  several  places.  This  anastomosing  and  bifurcating  effect  is  very  prominent 
throughout  an  exposure  traceable  for  nearly  two  hundred  feet.  In  places  the 
sill  contains  angular  fragments  of  limestone  which  usually  show  strong 
metamorphic  effects.  The  limestone  bordering  the  igneous  material  shows 
no  metamorphism  other  than  a  thin  darkened  band  about  a  sixteenth  of  an 
inch  in  thickness,  and  a  few  scattered  grains  of  pyrite.  Under  the  microscope, 
this  band  shows  a  recrystallizing  and  flattening  of  oolites2,  and  the  impregna- 
tion of  some  iron  oxides. 

1  See  Bain;  op.   cit.,   p.   29. 

2  The  texture  resulting  from  recrystallization  of  oolites  may  be  called  granospheritic, 
tUlowing  the  term  "granospherite"  as  used  by  Weinschenck  on  page  187  of  Petrographic 
Methods,  Weinschenck-Clark,  N.   Y.,   1912. 


240  GEOLOGY   OF    HARDIN    COUNTY 

The  sill  rock  is  aphanitic  porphyrinic  in  texture,  the  visible  phenocrysts 
being  phlogopite  or  biotite  and  augite.  While  the  mica  grains  are  scattered 
throughout,  there  is  a  slight  concentration  of  them  in  bands  close  to  and 
paralleling  the  contacts. 

Microscopically,  the  greater  part  of  the  rock  is  made  up  of  secondary 
calcite,  but  in  this  mass  appears  an  impressively  large  amount  of  fresh  apatite 
crystals  which  attain  unusual  sizes  for  fine-  or  medium-grained  igneous  rocks. 
Phlogopite  and  biotite  appear  as  very  prominent  phenocrysts,  and  their 
directions  of  elongation  are  commonly  parallel  to  the  sill  walls.  Some  of  the 
mica  grains  show  a  zonal  structure  of  moderately  pleochroic  material  sur- 
rounding very  strongly  pleochroic  substance.  Under  crossed  nicols  the  inner 
zone  shows  the  birefringence  colors  of  biotite  while  the  outer  zone  shows 
colors  intermediate  between  those  of  biotite  and  muscovite.  The  contact 
between  the  zones  is  not  indistinct  or  graded  as  might  be  the  case  were  the 
zoning  due  to  progressive  alteration  of  biotite  into  another  mica,  but  is  very 
sharp,  as  though  the  crystals  while  developing  in  the  magma  had  been  sud- 
denly deprived  of  their  iron  source,  changing  the  mica  at  this  point  from  an 
iron-rich  to  an  iron-poor  variety.  Grains  of  magnetite  or  other  iron  oxide 
minerals  are  very  abundant.  While  some  show  the  simple  isometric  sections  so 
characteristic  of  magnetite,  many  others  are  distinctly  skeletal  in  structure  as 
is  said  to  be  commonly  true  of  ilmenite.  Triangular  and  rhombic  sections  are 
common.  Augite  appears  as  phenocrysts  occasionally  partly  altered  to  horn- 
blende. Probably  augite  was  abundant  in  the  fresh  rock,  but  if  so  it  has 
since  been  greatly  altered.  No  feldspar  grains  are  to  be  seen;  if  ever  present 
— as  they  may  well  have  been — they  have  been  completely  changed.  Some 
of  the  finer-textured  alteration  products  are  distributed  in  such  a  fashion  as 
to  suggest  the  former  presence  of  lath-shaped  feldspars,  but  besides  this 
phenomenon  no  indication  is  given  as  to  the  feldspathic  character  o:f  the 
unchanged  mass.  Quartz  is  present,  undoubtedly  of  secondary  origin,  and 
probably  very  small  patches  of  serpentine.  A  rather  "dusty"-appearing  gray 
alteration  product  also  appears  in  small  irregular  patches,  commonly  asso- 
ciated with  what  is  probably  titaniferous  magnetite  or  ilmenite,  and  is  very 
likely  leucoxene.  This  substance  also  seems  to  mask  some  small,  vaguely 
outlined  areas  of  brownish  mineral  with  relatively  high  refraction,  which 
may  be  titanite.  The  identification  is  uncertain,  however.  Johannsen 
arranges  the  minerals  in  order  of  decreasing  prominence  as  follows:  "mica 
(chiefly  phlogopite),  pyroxene,  apatite,  iron  oxide,  and,  possibly,  perofskite." 
The  latter  mineral  was  not  seen  by  the  writer.  Pyrite  grains  in  small  quantity 
are  disseminated  through  the  rock.  The  rock  is  termed  lamprophi/re  as  no 
closer  classification  seems  possible. 

On  the  bluff  face  of  the  eastern  slope  of  this  hill  may  be  found  a  dike 
trending  a  little  west  of  north,  and  practically  vertical  in  attitude.  Its  width 
is  about  8  inches.     The  rock  is  so  completely  altered  as  to  give  no  suggestion 


IGNEOUS   ROCKS  241 

of  igneous  texture.  About  two  hundred  feet  north  by  west  from  this  ex- 
posure a  pile  of  debris,  stated  to  have  been  removed  from  a  well  dug  at  that 
point,  contains  an  abundance  of  fresh  igneous  rock  fragments  similar  in 
texture  and  composition  to  the  material  comprising  the  sill.  It  probably  rep- 
resents the  continuation  of  the  dike  at  the  bluff,  and  may  have  been  a  "feeder" 
for  the  sill  not  far  away. 

Mix  Dike. — On  the  Mix  farm  about  two  miles  north  of  Golconda,  in 
NE.  %  sec.  18,  T.  13  S.,  E.  7  E.,  a  dike  of  mica-peridotite  cuts  the  sandstone 
of  the  river  bluff  in  N.  35°  W.  direction.  The  rock  is  much  more  coarsely 
crystalline  than  "either  of  those  previously  described,  and  has  a  peculiarly 
mottled,  bronze  appearance,  due  to  the  large  amount  of  phlogopite  present, 
and  due  also  to  its  marked  poikilitic  texture.  Besides  mica,  the  hand  speci- 
men shows  small  scattered  grains  of  olivine,  grains  of  pyroxene,  and  much 
white  mineral  of  secondary  origin. 

Microscopically,  the  rock  contains  an  abundance  of  phlogopite,  serpentin- 
ized  olivine,  titanite,  and  black  opaque  oxides,  probably  magnetite  and 
ilmenite.  Subordinate  in  amounts  are  unaltered  olivine,  pyroxene  (partly 
altered  to  serpentine),  and  biotite.  Leucoxene  appears  as  an  alteration  pro- 
duct of  the  titaniferous  minerals.  Grains  closely  resembling  titanite  but 
possessing  no  double  refraction  are  probably  perovskite.  The  titanite  grains 
show  distinct  double  refraction.     Apatite  was  not  discovered  in  the  section. 

Golconda  Dike. — About  three-fourths  of  a  mile  southwest  of  the  railroad 
station  at  Golconda,  in  NW.  14  sec.  25,  T.  13  S.,  E.  7  E.,  a  dump  pile  of  an 
old  prospect  contains  fragments  of  a  medium-grained,  greenish-gray  igneous 
rock.  The  hand  specimen  displays  an  even-granular  texture.  The  color  of 
the  rock  is  due  to  secondary  minerals,  especially  serpentine. 

The  microscope  discovers  prominent  amounts  of  phlogopite,  pyroxene 
(diopside  ?),  and  serpentine,  the  latter  being  secondary  after  pyroxene  and, 
perhaps,  olivine.  No  olivine  grains  appear.  A  considerable  quantity  of  black 
opaque  minerals  is  disseminated  through  the  rock;  with  some  of  these  leu- 
coxene is  associated,  showing  that  both  ilmenite  and  magnetite  probably  make 
up  the  black  grains.  A  few  very  small  grains  of  either  titanite  or  perovskite 
are  found.  Feldspars  are  entirely  absent.  Johannsen  classifies  this  rock  as  a 
"pyroxene  lamprophyre,"  apparently  because  of  the  lack  of  olivine.  Olivine 
in  moderate  amounts  may  have  been  present  originally  and  may  now  be  repre- 
sented by  some  of  the  very  abundant  serpentine.  In  other  respects,  the  rock 
is  quite  similar  to  the  Mix  farm  peridotite,  with  the  exception  that  a  small 
amount  of  apatite  occurs  in  this  rock,  while  none  was  found  in  the  Mix  dike. 
In  both  rocks  the  mica  grains  have  a  poikilitic  texture. 

Soward  Intrusion. — On  the  Soward  farm  about  two  miles  northwest  of 
Rosiclare,  in  W.  i/2  sec.  31,  T.  12  S.,  E.  8  E.,  many  large  boulders  of  a  clastic 
igneous   rock    were   found.      Some    of    the    exposures    are   in   place.      Their 

—16  G 


242  GEOLOGY    OF    HARDIN    COUNTY 

distribution  suggests  an  elongated  area,  possibly  100  feet  in  width,  the  long 
axis  trending  northwesterly  up  the  hillside.     No  contacts  are  exposed. 

The  material  is  composed  of  a  highly  altered  fine-grained  matrix  carrying 
fragments  of  igneous  minerals  and  sedimentary  rocks.  Under  the  microscope 
a  texture  characteristic  of  volcanic  breccia  of  the  explosive  type  is  displayed. 
Large  rounded  sub-angular  and  angular  fragments  of  sedimentary  rocks  are 
embedded  in  the  volcanic  (?) 'matrix,  and  many  of  them  show  metamorphic 
effects. 

The  matrix  is  largely  indeterminable,  but  contains  angular  fragments  of 
mica,  quartz,  acid  plagioclase  (possibly  of  about  the  composition  of  andesine- 
oligoclase),  microcline  and,  perhaps,  orthoclase.  Some  of  the  mineral  grains 
contain  apatite  crystals,  and  zircon (?).     The  original  magma  was  evidently 


Pig.  16 — Panoramic  view  of  the  site  of  the  "volcanic  plug,"  half  a  mile  south 
southwest  of  Sparks  Hill,  Hardin  County,  Illinois,  in  the  NE.  %  NW.  %  NE.  % 
sec.  13,  T.  11  S.,  R.  8  E.  Known  area  of  plug  indicated  by  line.  Looking  north- 
west. 

of  acidic  type,  and  this  rock  may  represent  an  explosive  phase  of  the  region's 
igneous  phenomena. 

Sparks  Hill  Intrusion, — South  of  Sparks  Hill,  in  NE.  %  sec.  13,  T.  11 
S.,  R.  8  E.,  (figs.  16,  17,  and  18)  are  scattered  boulders  of  volcanic  breccia  so 
disposed  as  to  suggest  an  elliptical  area  of  igneous  rock  some  200  feet  long.1 

The  rock  contains  numerous  rounded  to  angular  fragments  of  sedi- 
mentary rocks,  some  of  which  show  metamorphic  effects.  The  ground  mass  is 
finely  clastic,  and  under  the  microscope  shows  angular  and  rounded  pieces  of 
quartz,  microcline,  orthoclase,  micas  (muscovite  especially),  and  plagioclase. 
Apatite  crystals  are  found  in  some  of  the  minerals.  Some  of  the  included 
rock  fragments  are  apparently  aphanitic  igneous  types.     Limestone  inclusions 

1  The  writer  did  not  observe  this  igneous  exposure,  but  received  his  information  re- 
garding it,  orally,   from  Mr.  Charles  Butts  of  the  U.   S.   Geological   Survey. 


IGNEOUS    ROCKS 


243 


Fig.  17. — Exposure  of  volcanic  rock  near  Sparks  Hill. 


Fig.  18. — View  of  a  mass  of  volcanic  rock  full  of  pebbles  of  many  kinds  of  rock 
near  Sparks  Hill.     Same  exposure  as  figure  17. 


244  GEOLOGY    OF    HARDIN    COUNTY 

are  frequently  altered — some  being  recrystallized,  and  others  partially 
quartzitized. 

The  rock  is  apparently  similar  in  composition  and  origin  to  the  Sowarcl 
farm  intrusion. 

Section  6,  T.  12  S.,  R.  8  E.,  1 'ntrusion.— In  the  north  half  of  this  section 
occurs  an  igneous  rock  of  clastic  character.  This  was  not  seen  by  the  writer, 
but  was  brought  to  his  attention  by  Dr.  U.  S.  Grant,  who  examined  it  in  the 
field,  and  who  placed  a  specimen  at  his  disposal. 

The  hand  specimen  displays  a  clastic  texture  in  which  large  included 
fragments  of  sediments  are  set.  Zonal  metamorphism  has  affected  these. 
Large  pieces  of  hornblende  and  biotite  are  conspicuous.  The  hornblende  is 
somewhat  rounded  in  shape  and  is  present  in  masses  up  to  about  one  inch  in 
diameter.  Much  pyrite  is  disseminated  through  the  larger  grains.  The 
biotite  appears  in  irregular  plates  up  to  one-half  inch  across. 

Microscopically  the  rock  is  very  much  altered,  mostly  to  calcite,  which 
condition  nearly  masks  the  original  texture.  Its  clastic  nature  can  be  seen, 
however.  In  the  matrix  appear  grains  of  feldspar,  pyroxene,  and  minute 
crystals  of  apatite.  The  latter  is  found  in  unusual  abundance  in  some  parts 
of  the  slides.  The  feldspar  grains  are  usually  so  altered  as  to  make  exact 
determination  of  variety  impossible,  but  a  few  fresh  pieces  showing  very 
narrow  and  closely  spaced  albite  twinning  striations  gave  very  low  extinction 
angles,  indicating  an  acidic  variety.  Some  grains  of  the  ground  mass  of  low 
birifringence  may  be  orthoclase,  while  a  few  others  give  faint  suggestions  of 
microcline  structure. 

The  original  rock  may  have  been  intermediate  in  its  composition  between 
the  peridotites  and  the  acidic  breccias  previously  described. 


PART  V 
ECONOMIC  GEOLOGY 


CHAPTER  XII— ECONOMIC  GEOLOGY 

Mineral  Resources 

The  principal  mineral  deposits  of  Hardin  County  are  veins  and  beds  of 
fluorspar.  Of  subordinate  importance  are  lead,  zinc,  iron  ore,  limestone,  and 
road  metal.  Soil  and  water  while  not  usually  classed  as  mineral  deposits,  still 
are  essentially  a  mineral  resource.  In  addition  to  these  there  is  also  a  possi- 
bility of  oil  and  gas,  although  the  presence  of  these  substances  has  not  been 
proven. 

Fluorspar,  Lead  and  Zinc 

By   L.  W.  Currier1 

GENERAL   STATEMENT 

Hardin  County  is  noted  for  its  deposits  of  fluorite,  which  are  the  largest 
and  most  important  in  the  United  States.  In  addition,  small  quantities  of 
lead  and  zinc  are  recovered  in  connection  with  the  mining  of  fluorite,  while 
limestone  and  clay  are  resources  of  local  interest.  The  fluorite  region  extends 
into  Pope  County,  adjoining,  and  across  Ohio  River  into  Kentucky,  but  the 
major  portion  of  the  output  is  taken  from  the  southwestern  part  of  Hardin 
County. 

BRIEF  HISTORY  OF  MINING  DEVELOPMENT 

Although  the  presence  of  fluorspar  in  southern  Illinois  was  known  in  the 
early  years  of  the  nineteenth  century,  no  mining  of  the  mineral  was  attempted 
until  1842.  In  that  year  Mr.  William  Pell  discovered  fluorspar  and  galena 
near  the  site  of  the -present  Rosiclare  mine  and  development  of  the  deposit  was 
undertaken.2  From  that  time  on,  mining  of  local  importance  was  prosecuted 
almost  continuously  in  the  district,  but  not  until  1870  or  thereabouts  were 
shipments  made.  Between  1870  and  1905,  Hardin  County  was  a  small  but 
almost  constant  producer.  Considerable  prospecting  was  done  during  this 
time,  but  most  of  the  mines  then  established,  being  at  a  distance  from  Ohio 
River  and  handicapped  by  transportation  difficulties,  found  it  impossible  to 
compete  with  the  large  veins  near  Rosiclare  and  were  consequently  abandoned. 

1  The  field  work,  on  which  this  portion  of  the  report  is  based,  was  carried  on  in 
August  and  September,  1917,  and  in  June,  1919.  To  the  owners  and  managers  of  the 
various  mines  the  writer  is  indebted  for  information  and  a  spirit  of  ready  cooperation. 
He  has  also  enjoyed  the  help  of  Dr.  Stuart  Weller  and  Mr.  Charles  Butts,  who  have  been 
engaged  in  a  stratigraphic  study  of  this  region,  and  is  indebted  to  Dr.  J.  E.  Pogue,  under 
whose   direction   the  field   work   was   prosecuted   and   this   portion   of   the   report   prepared. 

2H.  Foster  Bain,  The  fluorspar  deposits  of  southern  Illinois:  Bull.  255,  U.  S.  Geol. 
Surv.,   1905,   p.    12. 

247 


248  GEOLOGY    OF   HARDIN    COUNTY 

During  the  years  following  1905,  the  Rosiclare  and  Fairview  mines  and 
one  or  two  other  deposits  situated  at  some  distance  from  the  river,  among 
them  the  Pierce  Mines,  have  been  the  only  important  producers.  During  this 
period  and  particularly  since  1907,  there  has  been  a  steady  and  marked  climb 
in  output,  with  the  exception  of  a  slump  in  191-1,  due  to  the  falling  off  in 
production  of  open-hearth  steel  in  that  year.  The  rise  in  demand  and  prices 
created  by  the  course  of  the  war  has  not  only  greatly  stimulated  the  output 
of  the  large  mines,  but  has  been  responsible  for  the  reopening  of  some  of  the 
abandoned  mines  and  the  renewed  interest  in  prospecting  throughout  the 
country. 

THE  OCCURRENCE  OF  FLUORSPAR 

As  described  in  previous  chapters  Hardin  County  is  underlain  by  a  series 
of  horizontal  or  slightly  inclined  beds  of  limestone,  sandstone,  and  shale  of 
Chester  age  (Upper  Mississippian)  which  have  been  extensively  faulted.  The 
major  faults  trend  in  a  northeasterly  direction  and  these  are  crossed  by  a 
large  number  of  small  faults  running,  roughly,  northwesterly  to  westerly. 
The  faults  are,  almost  without  exception,  of  the  normal  or  gravity  type  (fig. 
3).  The  crustal  blocks  formed  by  this  system  of  intersecting  faults  have 
been  variously  displaced  and  slightly  tilted.  The  sediments  are  cut  in  a 
number  of  places  by  dikes  of  basic  igneous  rock.     (See  Plate  I  and  figure  19.) 

Some  of  the  fault  fissures  are  filled  with  mineral  matter,  the  minerals 
commonly  present  being  calcite,  fluorspar,  galena,  sphalerite,  and  others  in 
subordinate  amounts.  Calcite  is  the  most  widely  distributed  vein  mineral, 
in  many  instances  comprising  the  total  amount  of  the  vein  filling.  In  the 
workable  veins,  the  calcite  has  been  partly  or  wholly  replaced  by  fluorspar, 
accompanied  by  galena  and  sphalerite.  In  a  few  places,  especially  beneath 
impervious  rock  layers  and  in  close  proximity  to  fault  fissures^  beds  of  lime- 
stone have  been  partly  replaced  by  fluorite,  with  the  formation  of  flat  tabular 
deposits  of  this  mineral.  Many  of  the  vein  deposits  do  not  extend  to  the 
surface,  but  terminate  beneath  a  mantle  of  soil.  In  such  instances,  lumps  of 
the  relatively  insoluble  fluorspar  are  distributed  through  a  zone  of  clayey 
soil,  forming  a  superficial  or  so-called  "grave?7  deposit.  Thus  the  economic 
deposits  of  fluorspar  may  be  classified  as  (1)  vein  deposits,  (2)  bedding  de- 
posits, and   (3)   superficial  deposits. 

VEIN    DEPOSITS 

The  fluorspar  veins  constitute  the  most  important  type  of  deposit  in  the 
district.  They  owe  their  formation  to  the  circulation  of  mineralized  waters 
along  the  porous  channels  afforded  by  fissures  which  are  in  most  cases  dis- 
tinctly fault  fissures  or  zones.  Although  in  a  few  cases  the  veins  apparently 
occupy  simple  fissures,  faulted  fissures  of  more  or  less  displacement  seem  to 
have  been  the  most  accessible  channels  for  the  mineralizing  waters  and  the 
larger  veins  are  found   only  in  such  faulted  zones.     The  veins  conspicuous 


ECONOMIC   GEOLOGY 


249 


for  their  size  attain  extreme  widths  of  nearly  forty  feet,  and  the  average  vein 
reaches  a  width  of  five  to  fifteen  feet.  They  are  nearly  vertical,  the  most  im- 
portant running  in  a  northerly  or  northeasterly  direction,  and  lying  in  the 
limestone  and  sandstone  members  of  the  Chester  group. 


Scale  of  Miles 
1         2         3 

LEGEND 

®   Settlements 
X  Mines 
X  Prospects 
*   Igneous  Rocks 

1  Orrs  Landing  dike 

2  Rosiclare  quarry  dikes 

3  Downeys  Bluff  sill 

4  Mix  Farm  dike  *- 

5  Golconda  dike  - 
e  Clastic  dike 
7  Sparks  Hill  tuff 

^-'Faults 

and  veins 
19. — Sketch,  map  of  the  Illinois  fluorspar    district,    showing    locations    of 
mines  and  prospects,  igneous  rocks,  and  mineralized  faults  and  veins. 

The  most  productive  veins  are  near  Rosiclare,  on  the  properties  of  the 
Rosiclare  Lead  and  Fluorspar  Company  and  the  Fairview  Fluorspar  and  Lead 
Company.  The  main  working  of  the  former  company,  and  the  Good  Hope, 
Annex,  and  Extension  shafts  of  the  latter  are  on  the  largest  of  these  veins 


Fig 
principal 


250  GEOLOGY    OF    HARDIN    COUNTY 

from  which  the  majority  of  the  fluorspar  thus  far  produced  in  the  district  has 
been  taken. 

The  vein  of  the  Annex-Extension  mine  runs  about  north  and  south  near 
these  shafts,  and  turns  gradually  eastward  as  the  Good  Hope  workings  are 
approached.  The  drifts  of  the  Annex-Extension  mine  are  not  continuous  with 
those  of  the  Good  Hope,  though  a  level  of  each  has  been  recently  extended  to- 
within  150  feet  of  connecting.  In  the  Good  Hope  mine  and  other  mines  to 
the  northeast,  the  average  course  of  the  vein  is  nearly  N.  20°  E.  The  north- 
south  trend  of  the  vein  through  the  Annex-Extension  shafts  therefore  strongly 
suggested  at  first  that  they  might  have  been  located  on  a  separate  vein  inter- 
secting the  Good  Hope-Rosiclare  vein  at  a  fairly  sharp  angle,  but  this  sug- 
gestion appears  less  strong  in  view  of  the  recent  developments  just  mentioned 
above. 

From  a  third  to  a  half  mile  west  of  the  Good  Hope-Rosiclare  vein  is 
the  second  largest  vein  in  the  district,  the  Blue  Diggings  vein.  This  roughly 
parallels  the  Good  Hope-Rosiclare  vein.  A  few  rods  west  of  the  Blue  Diggings 
vein  is  a  fault  which  converges  with  the  Good  Hope-Rosiclare  vein  to  the 
north,  the  two  probably  uniting  at  a  point  half  a  mile  east  of  Stone  School 
and  two  miles  north  of  Rosiclare  just  south  of  the  Elizabethtown  road.  The 
mineralization  at  the  Daisy  mine  is  believed  to  be  associated  with  this  fault 
and  a  short  distance  northeast  of  the  point  of  intersection  is  an  outcrop  of 
fluorspar,  seven  or  eight  feet  wide,  bordered  by  quartzitic  sandstone  on  the 
west  and  limestone  on  the  east.  The  sandstone  forms  a  low  ridge,  due  to  its 
superior  resistance  to  erosion,  as  is  typical  of  sandstone  in  the  district  where 
bordering  a  fault.1  About  an  eighth  of  a  mile  beyond,  along  the  strike  of  the 
vein,  is  an  abandoned  mine  shaft,  with  a  dump  showing  coarse  calcite  and 
fluorspar  in  a  limestone  country  rock.  About  a  quarter  of  a  mile  farther 
along,  the  fault  is  terminated  by  a  cross-fault  running  X.  70°  E.,  according 
to  Weller. 

The  general  trend  of  most  of  the  veins  in  the  district  is  northeasterly. 
The  few  veins  that  run  in  a  northwest  direction  have  so  far  proven  to  bo  of 
minor  commercial  importance.  The  larger  veins  are  not  uniform  in  strike, 
but  display  the  long  sweeping  curves  characteristic  of  the  general  faulting 
of  the  district  (see  Plate  I). 

In  dip,  the  veins  are  steeply  inclined,  to  vertical.  The  Good  Hope- 
Rosiclare  vein  is  nearly  vertical,  here  and  there  changing  in  inclination  from 
steeply  west  to  steeply  east,  the  average  being  towards  the  west.  The  dip  of 
the  Blue  Diggings  vein  is  toward  the  east  and  very  variable,  becoming  less 
with  depth.     On  the  500-foot  level,  dips  of  55°  and  65°  were  observed. 

The  mineral  bodies  of  the  main  veins,  as  exposed  in  the  workings,  are 
thin  lenses  joined  to  one  another,  both  vertically  and  horizontally,  by  vein 

1  These  ridges,  due  to  silicification  of  sandstone  along  faults,  are  called  quartzite 
reefs,  by  Bain.  Bain,  H.  Fester,  The  fluorspar  deposits  of  southern  Illinois  :  TJ.  S.  Geol. 
Surv.   Bull.    255,   p.    33,   1905. 


ECONOMIC    GEOLOGY 


251 


material,  so  as  to  form  thin  tabular  masses  with  a  series  of  pinches  and 
swells.  Whether  viewed  along  the  course  of  a  drift,  or  from  successive  levels 
along  a  vertical  line,  the  developed  veins  show  variations  in  width  from  almost 
nothing  up  to  forty  feet.  Thus  in  the  Fairview  Company's  workings  in  the 
Annex-Extension  mine,  the  200-foot  level  extends  from  near  the  river  north- 
ward for  about  1,700  feet.  At  the  south  face  the  vein  width  is  7  feet;  from 
here  to  the  Annex  shaft,  a  distance  of  900  feet,  it  fluctuates  considerably, 
nearly  pinching  out  at  the  shaft  for  a  distance  of  25  feet;  it  then  widens 


Fig.  20. — Diagram  illustrating  the  effects  of  displacement  on  the  shape  of  a 
fault  fissure  when  the  fault  is  undulatory. 

The  arrows  show  directions  of  movement.  Where  the  movement  is  normal  to 
the  plane  of  the  fault,  namely  a  simple  stretching  apart,  no  variation  in  width 
of  the  fissure  results,  as  shown  in  A  above.  But  where  movement  in  another  direc- 
tion is  combined  with  the  stretching  movement  as  indicated  by  the  two  sets  of 
arrows  in  B,  the  fissure  will  vary  in  width.  In  Hardin  County  vertical  and  hori- 
zontal displacement  acting  in  this  way  is  responsible  for  the  characteristic  pinch- 
ing and  swelling,  and  the  lenticular  shape  of  the  mineral  matter  filling  the  fissure. 


considerably  attaining  a  maximum  of  30  feet,  but  pinches  again  to  almost 
nothing  at  the  north  face,  800  feet  from  the  shaft.  In  the  300-foot  level, 
which  is  about  1,000  feet  in  length,  similar  though  less  marked  conditions  of 
variations  are  to  be  seen,  indicating  pinching  and  swelling  in  a  vertical  direc- 
tion also. 

The  lenticular  shape  of  the  large  veins  is  attributed  to  the  slightly  un- 
dulatory character  of  the  fault  fissure  and  the  fact  that  the  walls  underwent 


252  GEOLOGY    OF   HARDIN    COUNTY 

a  slight  horizontal  movement  in  connection  with  an  extensive  vertical  dis- 
placement. The  resultant  zone,  which  subsequently  was  filled  with  mineral 
matter,  was  thus  given  a  variable  width,  as  is  diagiammatically  illustrated  in 
figure  20.  Indications  of  slight  horizontal  movement  are  found  in  nearly 
horizontal  striations  of  slickensides  on  the  vein  walls.  Such  striatums  are 
particularly  well  developed  in  the  Annex  and  Rosiclare  mines,  and  were 
observed  to  dip  slightly  to  the  north  in  some  instances,  and  to  the  south  in 
others.  Other  sets  with  nearly  vertical  striations  were  observed,  and  in  one 
place  the  horizontal  set  was  superimposed  on  the  vertical  set. 

Although  the  main  faulting  preceded  the  formation  of  the  veins,  minor 
faulting  movements  developed  later,  involving  the  vein  material.  These  move- 
ments were  of  two  types,  the  more  general  one  along  and  in  the  vein  matter; 
the  other,  across  the  vein. 

Movements  along  the  vein  are  indicated  by  a  persistent  plane,  or  by 
several  nearly  parallel  planes,  near  the  center  of  the  vein  matter.  In  places, 
this  surface  is  quite  smooth,  and  at  many  points  shows  fine  striations.  Quan- 
tities of  water  are  admitted  into  the  lower  workings  along  the  "center  slip" 
(see  figure  22),  as  the  chief  feature  of  this  kind  is  locally  called.  On  both 
sides  of  the  "center  slip,"  the  fluorspar  has  been  considerably  darkened  by 
the  deposition  of  galena  and  sphalerite.  In  some  places  the  sulphide  dis- 
semination and  minute  fracturing  have  taken  place  on  only  one  side  of  the 
slip,  the  spar  in  the  other  side  remaining  fairly  clear. 

Cross-faulting  within  the  vein  is  not  pronounced,  although  minor  frac- 
tures and  displacements  are  noticeable  here  and  there.  The  most  conspicuous 
example  of  such  movement  was  found  near  the  south  face  of  the  200-foot  level 
of  the  Blue  Diggings  mine,  where  the  vein  has  been  completely  cut  off  by  a 
cross  fault. 

As  indicated  by  the  disposition  of  the  wall-rocks,  the  continuation  of  the 
vein  may  probably  be  picked  up  by  drifting  in  a  direction  running,  a  few 
degrees  south  of  west.  Cross-faulting  appears  to  have  been  a  distinctly  more 
common  occurrence  on  the  Blue  Diggings  vein  than  on  the  Good  Hope- 
Resiclare  vein. 

MINERALS   OF  THE  VEINS 

Fluorspar. — Other  names,  fluorite  and  spar.  Composition,  calcium 
fluoride;  51.3%  calcium,  48.7%  fluorine.  Glassy  luster;  easily  scratched  by 
knife  blade ;  perfect  cleavage ;  massive  or  in  cubic  crystals. 

Fluorspar  occurs  in  great  masses,  breaking  into  angular  cleavage  pieces 
upon  being  mined,  and  in  crystals  and  crystal  groups.  In  Hardin  County 
the  bulk  of  the  mineral  is  colorless  to  white  or  to  faintly  yellowish,  but  shades 
of  purple,  amber,  green,  and  blue  are  also  common.  It  is  closely  associated 
with  white  crystalline  calcite,  which  it  replaces.  Some  of  the  material  runs 
in  purity  above  98%,  although  the  common  intimate  association  with  galena, 
sphalerite,  and  calcite,  makes  it  necessary  to  mill  the  product  before  shipment. 


ECONOMIC    GEOLOGY  253 

Calcite. — This  mineral,  calcium  carbonate,  known  locally  as  calc,  is 
readily  recognized  by  its  rhombic  cleavage,  and  occurs  in  massive  form  in 
close  association  with  fluorspar,  as  well  as  alone,  as  a  vein-filling  material.  It 
is  also  found  as  small  scalenohedral  crystals  occupying  cavities  in  the  veins. 
Veinlets  of  calcite  are  observed  in  association  with  some  of  the  dikes  of  the 
region.  In  the  fluorspar  veins,  it  is  generally  white,  coarse-grained,  and 
partly  replaced  by  fluorspar.  While  it  occurs  in  all  portions  of  the  veins,  it 
tends  to  be  gathered  near  the  walls,  the  fluorspar  thus  occurring  between  two 
bands  of  calcite,  although  masses  and  bands  are  also  included  within  the 
fluorspar.  Small  veinlets  of  calcite,  evidently  of  a  later  generation,  cut  the 
massive  fluorspar,  here  and  there,  in  the  main  veins. 

Quantities  of  calcite  are  rejected  as  waste  from  the  mills. 

Galena. — This  mineral,  the  sulphide  of  lead,  black,  heavy,  with  perfect 
cubic  cleavage,  is  the  most  abundant  sulphide,  occurring  as  disseminated 
grains  and  as  veinlets,  in  the  vein  fluorspar.  It  is  nowhere  in  sufficient  abund- 
ance to  be  mined  directly,  but  a  small  quantity  is  recovered  in  connection  with 
the  milling  of  fluorspar,  and  is  sold.  It  is  usually  associated  with  sphalerite 
and  chalcopyrite;  and  in  cavities  in  the  veins,  small  crystals,  showing  the 
faces  of  the  cube  and  octahedron,  are  often  found. 

In  the  veins,  the  mineral  tends  to  be  most  abundant  near  the  center,  and 
particularly  in  places  where  slip  planes,  or  "center  slips,"  are  pronounced  and 
numerous.  Its  general  disposition  is  such  as  to  suggest  its  introduction 
toward  the  close  of  the  period  of  mineralization,  after  the  fluorspar  had  been 
mainly  deposited.  Its  intimate  association  with  sphalerite  and  chalcopyrite 
suggests  a  formation  practically  simultaneous  with  these  minerals. 

This  galena  is  more  notably  argentiferous  than  the  galena  of  other 
deposits  of  the  Mississippi  Valley.  Silver  values  up  to  14  ounces  per  ton 
have  been  reported.1 

Sphalerite. — This  mineral,  the  sulphide  of  zinc,  also  known  as  "blende" 
or  "jack,"  occurs  in  close  association  with  galena,  though  in  somewhat  less 
abundance.  It  is  found  as  small  masses,  grains,  and  seamlets  enclosed  in  the 
fluorspar,  and  is  rarely  unaccompanied  by  grains  of  galena  and  chalcopyrite. 
In  no  place  is  it  sufficiently  concentrated  to  warrant  its  exploitation  alone. 
It  has  been  recovered  thus  far  only  by  hand-picking,  in  connection  with  the 
milling  of  fluorspar,  but  experiments  have  recently  been  carried  on  looking 
to  its  recovery  from  the  mill  flows,  where  it  appears  in  the  table  middlings. 
Since  its  specific  gravity  is  only  slightly  greater  than  that  of  fluorspar,  neither 
table  nor  jig  concentration  is  able  to  make  a  clean  separation  of  the  two. 
This  separation,  may,  perhaps,  be  effected  by  flotation  methods,  in  which 
event  a  quantity  of  otherwise  useless  middlings  will  yield  a  by-product  of 
value.  In  small  cavities  in  the  veins,  minute  crystals  of  sphalerite  are  found 
showing  intricate  crystal  forms. 

1  See  Bain,   op.  cit.,   p.   38. 


254  GEOLOGY    OF   HABDIN    COUNTY 

Chalcopyrite. — The  yellow  sulphide  of  copper  and  iron  is  present  in  sub- 
ordinate amounts  as  a  common  associate  of  galena  and  sphalerite.  It  is 
found  as  small  grains,  both  alone  in  the  fluorite  and  amongst  the  other 
sulphides.    Its  quantity  is  nowhere  sufficient  to  lend  it  commercial  importance. 

Hydrocarbon. — A  conspicuous  quantity  of  black,  flaky,  bituminous  ma- 
terial, having  an  odor  resembling  that  of  petroleum,  is  found  here  and  there 
in  the  veins,  in  cavities,  in  the  calcite,  and  in  the  fluorspar.  A  similar 
material  occurs  in  the  calcite  veins  associated  with  the  dike  at  Orrs  Landing. 

Other  Minerals. — Other  minerals  seen  or  reported  in  connection  with  the 
veins  are  barite,  pyrite,  malachite,  and  stibnite.  Barite  occurs  in  small 
amounts  associated  with  the  fluorspar  and  an  occasional,  well-formed  crystal 
may  be  found  in  cavities  in  the  veins.  Pyrite  is  found  as  small  veins  in- 
conspicuously disseminated  in  the  wall  rocks  and  vein  matter.  Malachite  is 
noted  as  a  staining  in  a  few  places  in  the  veins,  and  represents  a  local  altera- 
tion of  the  chalcopyrite.  Stibnite1,  the  sulphide  of  antimony,  has  been 
reported  to  be  present  in  the  Fairview  mine,  but  its  occurrence  was  not 
verified  by  the  present  writer. 

BEDDING   DEPOSITS 

In  places  fluorspar  occurs  in  flat-lying  tabular  masses,  forming  part  of 
the  series  of  sedimentary  rocks.  Such  occurrences  are  not  so  abundant  as  the 
veins,  and  owing  to  the  thinness  and  impurities  of  these  bodies,  they  have 
been  subjected  to  fitful  rather  than  continuous  exploitation.  Occurrences  of 
this  type  may  be  termed  bedding  deposits.  Locally  they  are  called  "blanket" 
formations. 

These  deposits  are  replacement  bodies  along  the  stratification  planes  of 
limestone  beds.  They  are  found  in  places  where  a  porous  layer  of  limestone, 
under  a  relatively  impervious  bed,  was  made  accessible  to  ore-bearing  solu- 
tions through  an  intersecting  fissure  or  fault.  Because  of  this  relationship, 
they  may  be  expected  to  be  relatively  long  and  narrow.  One  of  these  deposits, 
developed  in  the  west  side  of  Lead  Hill  apparently  continues  through  the 
hill,  outcropping  on  the  east  side  at  a  horizontal  distance  of  about  1,000  feet 
from  the  entrance  workings.  Some  of  the  smaller  vein  deposits  are  associated 
with  this  type. 

The  most  characteristic  feature  of  the  ore  occurrence  in  the  bedding  type 
of  deposit  is  a  conspicuous  horizontal  banding,  which  is  due  to  the  alternation 
of  layers  of  pure  crystalline  fluorspar  with  layers  of  finer-grained,  sandy- 
looking  and  less  pure  fluorspar,  or  partially  replaced  limestone,  or  crystalline 
quartz.  Layers  of  quartz  are  particularly  detrimental,  because  where  they 
form  a  prominent  part  of  the  deposit  its  successful  exploitation  is  prevented. 
The  bands  of  the  bedding  deposits  are  rather  evenly  spaced  and  fairly  uniform 
in  thickness  in  any  one  deposit.     The  bands  are  not  continuous  through  long 

1  See   Bain,   op.   cit.,   p.   39. 


ECONOMIC    GEOLOGY  255 

distances,  but  thin  out  or  widen  and  bifurcate,  finally  being  terminated 
abruptly  by  some  minor  structural  feature,  such  as  a  joint  crack  filled 
with  clay,  a  thin  bed  of  clay,  or  a  silicified  rock ;  or  else  finally  thinning  grad- 
ually into  disappearance  within  the  limestone  bed.  The  layers  are  usually 
V-2  to  %  of  an  inch  thick,  though  bands  of  greater  thickness  are  often  found. 
The  clear  fluorspar  layers  are  of  high  purity.  The  mineral  is  generally  tinted 
with  shades  of  red,  purple,  or  blue,  but  in  some  places  much  of  it  is  practically 
colorless.  The  layers  which  alternate  with  the  clear  fluorspar  are  more  com- 
monly brownish-gray,  porous,  and  granular,  representing  in  some  places  iron- 
stained  and  silicified  limestone  only  partly  replaced  by  fluorspar;  in  other 
cases  they  are  composed  almost  entirely  of  "spar/'  In  a  few  instances,  as 
mentioned  above,  the  impure  granular  layers  are  entirely  lacking,  their  place 
being  occupied  by  clear  and  well-crystallized  quartz.  Galena  is  present  as 
small  grains  in  the  impure  bands,  and  as  cubes  within  and  bordering  the 
pure  bands.  Sphalerite  is  also  present  but  in  much  less  amount  than  is  the 
galena.  In  cavities  where  crystals  of  fluorite  have  formed,  the  crystal  faces 
are  sometimes  found  with  a  coating  of  yellow  zinc  carbonate,  locally  known  as 
"turkey  fat"  ore.  In  places  the  galena  shows  marked  alteration  to  cerussite, 
the  carbonate  of  lead. 

The  Lead  Hill  deposit  occupies  a  zone  directly  beneath  a  layer  of  dense 
limestone.  Near  the  entrance  to  the  northern  of  the  two  tunnels  running 
into  the  hill,  the  horizontal  mass  of  fluorite  is  seen  to  pass  downward,  funnel- 
shaped,  into  a  narrow  vein,  which  evidently  represents  the  channel  followed 
by  the  ore-bearing  solutions. 

The  minerals  found  in  the  bedding  deposits  are  fluorspar,  quartz,  galena, 
smithsonite,  and  cerussite.  Calcite  is  noticeably  lacking  except  for  a  few 
small  crystals  in  cavities.  As  compared  with  the  amounts  found  in  veins, 
galena  is  very  unimportant  except  in  a  few  places — as  in  parts  of  the  Lead 
Hill  deposit  where  large  cubes  are  obtainable  in  sufficient  supply  to  be 
separated,  and  at  the  Miller  mine  near  Melcher  Hills,  where  small  veins 
merge  into  a  bedding  deposit.  While  sphalerite  appears  to  be  rare,  zinc  car- 
bonate is  often  found  as  described  above.  It  is  never  sufficiently  abundant, 
however,  to  be  of  primary  economic  value. 

As'  contrasted  with  the  massive  fluorspar  of  the  vein  type  deposits,  the 
fluorspar  of  the  bedding  deposits  is  crystalline  and  transparent.  Most  of  it 
is  colored  or  tinted  as  noted  previously,  and  many  beautiful  specimens  of  the 
crystals  which  would  make  excellent  museum  material  may  be  found  readily. 
Such  localities  give  considerable  promise  as  sources  of  optical  spar. 

The  bedding  deposits  have  not  been  developed  extensively,  partly  because 
of  the  lack  of  promise  of  continuity  for  any  distance,  and  probably  also 
because  of  the  difficulty  in  separating  the  higher  grade  fluorspar  from  the 
interbanded  material  of  poorer  quality.  Where  the  interbands  are  of  quartz, 
moreover,  the  deposit  is  likely  to  have  no  industrial  value.     Also  the  general 


256  GEOLOGY    OF    HARDIN    COUNTY 

thinness  of  the  deposits  would  be  apt  to  make  mining  unprofitable  because 
development  similar  to  the  room-and-pillar  method  of  mining  would  be 
necessary. 

SUPERFICIAL  DEPOSITS 

A  small  part  of  the  fluorspar  of  the  district  is  won  from  surface  pits  and 
trenches,  the  deposits  thus  mined  being  known  locally  as  "gravel"  deposits, 
because  they  consist  of  fragments  of  fluorspar  scattered  through  a  clayey  or 
sandy  soil.  The  material  is  commonly  dug  out  by  pick  and  shovel  and 
washed  in  log-washers  or  in  concrete  mixers,  the  product  going  by  the  name 
of  "gravel  spar."  The  product  is,  however,  distinctly  different  from  the 
gravel  spar  recovered  in  the  Eosiclare  and  Fairview  mills,  and  the  two  should 
not  be  confused. 

The  matrix  of  the  fluorspar  in  these  deposits  is  usually  the  red  clay  that 
results  from  the  weathering  of  the  limestone  bed-rock,  by  which  process  the 
major  portion  of  tbe  limestone,  consisting  of  calcium  carbonate,  has  been 
dissolved  and  removed  by  surface  waters,  leaving  the  relatively  insoluble  clay 
and  fluorspar  behind  as  deposits  in  the  soil  mantle.  In  this  way  solid  veins 
of  fluorspar  are  converted  into  zones  of  weathered  material  carrying  a  con- 
spicuous quantity  of  fluorspar  fragments. 

The  distribution  of  the  surface  workings  of  many  of  the  superficial 
deposits  indicates  the  position  of  well-defined  veins  below.  The  size  of  these 
veins,  however,  cannot  always  be  judged  from  the  richness  of  the  surface 
workings,  since  a  given  gravel  deposit  may  represent  a  considerable  concen- 
tration of  fluorspar  from  the  extensive  erosion  of  a  small  vein. 

Many  of  the  superficial  deposits  yield  a  very  high-grade  product,  the 
processes  of  formation  having  served  to  remove  the  impurities  usually  present 
in  the  veins.  Moreover,  this  type  of  deposit  may  be  worked  at  small  initial 
and  running  expense,  and  is  therefore  adapted  to  exploitation  with  little 
capital.  For  these  reasons,  the  gravel  deposits  may  be  expected  to  compete 
in  a  small  way  with  the  larger  veins  requiring  more  extensive  mining  equip- 
ment. 

The  Pierce  mines,  in  Pope  County,  about  ten  miles  north  of  Golconda, 
are  interesting  and  characteristic  examples  of  this  type  of  deposit.  The  open- 
pit  development  (fig.  21)  points  to  the  existence  of  two  veins,  one  running 
about  N.  75°  E.,  the  other  about  N.  45°  E.  The  deposits  have  been  opened, 
for  the  most  part,  only  at  the  surface,  and  show  the  usual  dissemination  of 
fluorspar  in  red  clay  and  in  sandy  clay.  'Near  the  bottom  in  some  parts  of  the 
pits  the  spar  appears  less  disseminated  and  more  vein-like  in  structure. 
Occasional  rounded  boulders  of  limestone  are  encountered  in  excavating,  some 
of  which  are  cut  by  narrow  stringers  of  calcite  and  fluorspar.  Coarse  calcite 
remnants  together  with  fluorspar  are  also  found  in  these  boulders,  the  asso- 
ciation pattern  resembling  that  found  in  the  Fairview  and  Eosiclare  veins — 
that  is,  the  replacement  of  calcite  by  fluorspar.     The  fluorspar  is  remarkably 


ECONOMIC    GEOLOGY 


257 


clear  and  pure,  nearly  transparent,  tinted  in  shades  of  red,  blue,  and  purple, 
thus  differing  from  the  fluorspar  of  the  Eosiclare  and  Fairview  mines  which 
is  translucent  to  opaque  and  mostly  white,  yellow,  or  brown.  Large  cleavage 
pieces  nearly  a  foot  in  diameter  were  seen  by  the  writer.  Optical  fluorspar 
is  said  to  have  been  obtained  from  the  Pierce  deposits,  which  indeed  show 
indications  of  being  a  very  probable. source  of  such  spar.     . 


MILL 


k 


SCALE 


100 

i 


200 

i 


3J°   FEET 


Fig.  21. — Map  showing  the  distribution  of  the  principal  open-cuts  of  the  Pierce 
Mines  and  the  apparent  directions  of  the  veins. 

PARAGENESIS    OF    MINERALS 

Underground  observations  and  microscopic  examinations  of  polished 
surfaces  of  specimens  from  various  parts  of  the  veins,  particularly  from  the 
Annex,  Blue  Diggings,  and  Eosiclare  mines,  disclose  the  following  relations 
regarding  the  order  of  mineral  deposition  in  the  veins. 

1.  Calcite  appears  to  have  been  the  first  mineral  deposited  in  the 
fissures1.  It  is  generally  of  very  coarse  texture,  milky  white,  and  is  present 
throughout  the  workings.     Very  few  parts  of  the  veins  lack  this  mineral, 

1  It   is   not   at   all   probable,   however,   that  the   calcite   was   deposited   from   the    same 
waters,  or  even  waters  of  similar  origin,  that  deposited  the  flourspar. 


-17  G 


258 


GEOLOGY    OF    HARDIN    COUNTY 


though  the  amount  to  be  found  is  extremely  variable.     It  is  found  especially 
along  both  walls  of  the  veins,  with  fluorspar  occupying  the  central  zone. 

2.  Fluorspar  is  the  second  mineral  of  deposition,  unmistakably  replacing 
calcite.  Masses  and  rhombs  of  calcite  are  found  in  great  abundance  showing 
every  stage  in  the  process  of  replacement. 

3.  The  sulphides  of  lead,  zinc,  and  copper — galena,  sphalerite,  and 
chalcopyrite,  respectively — were  probably  deposited  nearly  simultaneously  after 
the  fluorspar,  although  some  initial  deposition  may  have  accompanied  the 
formation  of  the  fluorspar,  since  in  many  places  they  are  found  disseminated 
through,  and  entirely  surrounded  by,  the  spar.  In  general,  however,  they  were 
deposited  along  fractures  in  the  fluorspar,  being  introduced  along  the  "slip" 
planes;  and  in  all  such  instances  they  are  clearly  subsequent  to  the  fluorspar. 


Fig.  22. — Idealized  section  of  a  fluorspar  vein,  showing  general  relations  be- 
tween wall  rock,  minerals,  and  "center  slips."  The  white  areas  are  calcite,  the 
stippled  areas  fluorspar,  and  the  blackened  areas  sulphides. 


No  well-marked  stages  in  the  deposition  of  the  individual  sulphides  are 
apparent.  While  some  specimens  seem  to  indicate  that  sphalerite  preceded 
galena,  this  observation  is  reversed  upon  examination  of  other  specimens.  In 
most  examples,  the  intergrowth  of  the  two  is  such  as  to  imply  simultaneous 
deposition.  In  some  parts  of  the  veins  only  one  of  these  two  minerals  occurs, 
while  in  other  parts  both  are  prominent.  The  latter  condition  renders  diffi- 
cult the  problem  of  recovering  both  sulphides  as  by-products  in  the  milling 
operations. 

4.  Second  and  later  generations  of  both  calcite  and  fluorspar  are  present, 
but  in  very  minor  quantities,  being  developed  especially  in  open  cavities  of 
the  veins  and  walls.  Quartz  is  also  found  in  association  with  these  later 
generations.  No  indications  of  the  secondary  enrichment  of  the  sulphide 
minerals  were  seen. 


ECONOMIC    GEOLOGY  259 

Figure  22  is  an  idealized  section  of  the  large  veins  showing  the  mineral 
relations. 

In  the  bedding  deposits  the  same  order  of  deposition  as  outlined  above 
seems  to  have  been  followed,  except  that  the  first  generation  of  calcite  is 
absent.  The  carbonates  of  zinc  and  lead — smithsonite  and  cerussite — 
represent  the  latest  deposition,  being  the  result  of  oxidizing  waters  of  the 
meteoric  circulation.  Sphalerite  is  never  prominent  in  the  bedding  deposits, 
but  galena  is  in  some  places  abundant  and  occurs  as  well-formed  crystals. 

METASOMATIC  RELATIONS  OF  MINERALS 

The  accompanying  photomicrographs  (Plate  II)  of  specimens  obtained 
at  the  Eosiclare  and  Fairview  mines  illustrate  some  of  the  replacement 
features. 

A  study  of  many  specimens  discloses  the  same  general  paragenetic  features 
for  all.  The  fluorite  is  seen  everywhere  to  replace  the  original  vein  calcite  or 
the  wall-rock  material  itself  where  the  latter  is  predominantly  calcareous. 
No  instance  was  seen  of  any  replacement  of  sandstone  or  quartzite  wall-rock 
by  fluorite  with  the  exception  of  cases  where  the  rock  appears  to  be  a  silicified 
limestone.  '.Whether  or  not  such  silicification  took  place  partly  or  entirely 
subsequent  to  the  deposition  of  fluorite  is.  not  evident. 

Quartz  appears  prominently  in  some  of  the  specimens.  The  major  por- 
tion of  it  is  certainly  subsequent  to  the  fluorite,  but  there  are  suggestions  of 
contemporaneity  of  the  two  in  some  places.  It  is  quite  likely  that  the  precipi- 
tation of  silica  began  before  the  deposition  of  fluorite  was  completed.  Quartz 
also  appears  to  be  subsequent  to  the  sulphides,  suggesting  a  long  range  of 
deposition  as  compared  with  the  other  minerals.  The  quartz  is  glassy,  clear, 
and  crystalline,  and  not  chalcedonic  or  very  fine-grained  as  is  so  generally 
the  case  with  many  shallow-depth  veins. 

The  sulphides  are  probably  of  nearly-  contemporaneous  deposition,  and  are 
closely  related  to  fractures  in  the  calcite  and  fluorite,  replacing  both  of  these 
minerals.  The  galena  not  infrequently  appears  with  strongly  idiomorphic 
outlines. 

It  is  often  difficult  under  the  microscope,  if  not  impossible  in  some  cases, 
to  determine  exact  limits  between  fluorite  and  calcite.  This  is  partly  due  to 
their  similarity  in  appearance,  though  the  larger  masses  may  be  easily 
recognized  by  their  cleavages  and  the  marked  dispersion  of  colors  of  the 
fractured  fluorite.  A  very  strong  and  intricate  intergrowth  with  gradual 
shading  from  one  mineral  to  the  other  is  common. 

The  following  tabulation  gives  the  replacement  relationships  between  the 
minerals  of  the  veins.    In  the  bedding  deposits,  only  those  marked  (*)  apply. 


260  GEOLOGY    OF    HARDIN    COUNTY 

Calcite  replacing  limestone 
*Fluorite  replacing  limestone 
Fluorite  replacing  calcite 
Sulphides  replacing  limestone 
Sulphides  replacing  calcite 
Sulphides  replacing  fluorite 
*  Quartz  replacing  limestone 
Quartz  replacing  calcite 
The  very  generalized  time  relationships  between  the  minerals  are  dia- 
grammatically  expressed  in  the  lower  figure  of  Plate  II-G,  where  the  abscissae 
measure   paragenetic   time,   and   the   vertical    dimensions   of   the   individual 
mineral   plots   indicate   relative   amounts,   not   computed,   of   the   respective 
minerals. 

DESCRIPTION    OF   PHOTOMICROGRAPHS    AND    FIGURES    ILLUSTRATING   PARAGEJNESIS 

Some  of  the  most  decisive  replacement  patterns  are  shown  in  the  thin 
sections.  The  features  shown  by  the  best  one  of  the  sections  studied  are 
worthy  of  brief  description.  In  thin  section,  fluorite  is  seen  to  penetrate 
calcite  irregularly  as  veinlets  which  sometimes  terminate  with  idiomorphic 
outlines.  Slight  projections  of  the  fluorite  along  calcite  crystallographic 
directions  may  be  observed,  as  though  the  fluorite  was  controlled  by  calcite 
twinning  to  a  small  degree,  though  more  commonly  the  fluorite  does  not  show 
this  directional  replacement  but  rather  enlarges  irregular  calcite  boundaries. 
Galena  displays  the  finest  replacement  pattern  observed,  where  it  is  developed 
in  a  lattice-like  pattern  following  very  definitely  the  twinning  directions  of 
calcite.  A  photomicrograph  of  this  is  shown.  Elsewhere  galena  shows  idio- 
morphic outlines  where  it  is  in  contact  with  sphalerite  on  one  side  and  with 
calcite  on  the  other.  Fluorite  appears  entirely  enclosed  by  galena,  especially 
along  a  fracture  between  fluorspar  and  calcite  grains.  In  some  places  galena 
also  completely  surrounds  small  patches  of  sphalerite. 


Illinois  State  Geological  Sukvey 


Bulletin  No.  41,  Plate  II-A 


A.  Quartz  (Q),  chalcopyrite  (Ch),  and  galena  (G),  replacing  calcite  (Ca). 
No  definite  order  among  the  sulphides  is  suggested.  The  galena  is  seen  to  be  idio- 
morphic.  The  same  specimen  in  other  portions  shows  replacement  of  calcite  by 
fluorite  and  of  fluorite  by  sulphides.  The  transition  from  fluorite  to  calcite,  while 
sometimes  sharp,  generally  is  indistinct  or  gradual.  Elsewhere,  also,  the  specimen 
suggests  that  some  quartz  deposition  accompanied  the  fluorite;  much  was  closely 
following  and  preceded  the  sulphides,  and  some  may  have  followed  the  sulphides. 
The  black  spots  in  the  key — corresponding  to  numerous  very  small  white  areas  in 
the  photomicrograph — represent  blende. 


Quartz   (Q),  sphalerite   (blende)    (B)   and  calcite   (Ca), 
Magnification  150  diameters. 


Illinois  State  Geological  Survey 


Bulletin  No.  41,  Plate  II-C 


A.  Veinlet  of  fluorite  (P)  containing  later  sulphides  in  silicified  limestone 
(L).  A  transition  zone  into  wall-rock  material  is  indicated.  The  rock  contains 
also  many  specks,  apparently  of  fluorite. 


B.  Section  in  a  small  veinlet  cutting  an  argillaceous  limestone  wall-rock, 
showing  relationships  between  wall-rock  material  (W),  fluorite  (F),  galena  (G), 
and  chalcopyrite  (Ch).  The  wall-rock  contact  with  fluorite  is  very  irregular  and 
vague,  and  the  fluorite  mass  contains  many  minute  fragments  besides  the  larger 
remnants  indicated. 


Illinois  State  Geological  Survey 


Bulletin  No.  41,  Plate  II-E 


A.  Sphalerite  (S)  here  replaces  calcite  (Ca)  along  twinning  directions  and 
fluorite  (F)  cleavage  directions.  The  metasomatic  relations  between  these  are 
considered  very  strongly  indicated. 

Also  to  be  noted  are  the  various  included  grains,  the  idiomorphic  quartz  (Q) 
section  showing  nearly  included  sphalerite  (S),  though  the  inclusion  is  close 
enough  to  the  larger  sphalerite  mass  to  be  a  possible  tongue  of  the  latter.  On  the 
extreme  right,  the  line  of  contact  between  calcite  and  fluorite  is  very  irregular  and 
can  not  be  followed  in  the  photograph,  though  it  appears  distinctly  outlined  in 
the  section.  The  fluorite  areas  are  portions  of  a  zone  filling  and  replacing  along 
a  fracture  zone  in  coarse-grained  calcite,  in  which  are  also  found  several  idio- 
morphic quartz  grains. 

Magnification  250  diameters. 


B.     Reduced  scale  of  figure  A,  showing  its  relation  to  larger  mass  of  sphalerite 
and  to  fluorite  veinlet. 

Magnification  40  diameters. 


Illinois  State  Geological  Survey 


Bulletin  No.  41,  Plate  II-G 


A.  The  principal  feature  of  this  figure  is  replacement  of  calcite  (Ca)  by 
quartz  (Q)  along  twinning  directions  of  the  former.  Galena  (G)  and  sphalerite 
(S)  also  appear  replacing  calcite  in  the  common  manner — the  galena  with  partial 
idiomorphic  outlines  in  places,  the  sphalerite  in  irregular  masses  extending  short 
distances  along  calcite  twinning  striations.  In  this  figure  quartz  includes  both 
sulphides. 

Fluorite  (F)  here  replaces  calcite.  In  adjacent  areas— just  out  of  this  field— 
fluorite  is  to  be  seen  plainly  replaced  by  the  sulphides. 

Magnification  50  diameters. 


Calcite 

Fluorite 

Chalcopyrite 

Pyrite 

Sphalerite 

Galena 

Quartz 


B.  Shows  the  very  generalized  time  relationships  between  the  minerals,  as 
worked  out  from  a  study  of  thin  sections  and  polished  surfaces.  The  abscissae 
measure  paragenetic  time,  and  the  vertical  dimensions  of  the  individual  mineral 
plots  indicate  relative  amounts,  not  computed,  of  the  respective  minerals. 

—18  G 


ECONOMIC    GEOLOGY  275 

ORIGIN  OF  THE  DEPOSITS 
VIEWS    OF   PREVIOUS    WRITERS 

Lead  and  zinc  deposits  occur  in  a  number  of  localities  in  the  Mississippi 
Valley,  notably  in  southwest  Wisconsin  and  in  Missouri,  where  the  weight  of 
evidence  is  undeniably  in  favor  of  an  origin  from  meteoric  waters  circulating 
under  artesian  conditions  and  leaching  their  metallic  contents  from  a  wide 
area  of  sediments.1  The  lead  of  these  regions  is  notably  lacking  in  silver 
content.  Fluorspar  is  lacking.  The  deposits  are  not  of  the  fissure  vein  type, 
but  rather  are  gash  veins  and  bedding  replacements  in  definite  horizons. 
Finally,  faulting  and  igneous  rocks  are  absent,  at  least  as  conspicuous 
structural  features. 

The  Hardin  County  region,  however,  is  seen  to  present  contrasting 
features  throughout,  as  compared  with  the  Missouri  and  Wisconsin  regions. 
In  the  former,  faulting  is  pronounced  and  the  fault  fissures  contain  the  most 
concentrated  values  in  the  form  of  fissure  veins.  The  most  abundant  mineral 
is  fluorite,  a  substance  known  to  have  a  strong  igneous  affiliation,  and  the 
galena  is  argentiferous,  which  is  commonly  true  of  lead  deposits  that  are 
formed  by  deposition  from  thermal  solutions  ascending  from  below  and 
having  more  or  less  direct  igneous  connections.  'Finally,  the  presence  of 
igneous  rocks  in  the  district  gives  it  petrologic  distinction.  The  points  of 
contrast  between  these  two  types  of  lead-zinc  regions  are  of  high  significance, 
indicating  with  little  or  no  uncertainty  the  origin  of  these  fluorspar-lead-zinc 
deposits  by  thermal  ascending  solutions  as  opposed  to  meteoric  waters.2 

Emmons,  who  examined  the  Illinois  deposits  in  18923,  attributed  their 
formation  to  material  leached  from  the  surrounding  limestone.  It  is  difficult 
to  conceive,  in  this  connection,  that  circulating  ground  waters  obtaining  a 
load  in  this  manner  would  have  selected  certain  fractures  for  deposition  of 
minerals  leaving  many  others  entirely  unaffected.  Such  water  would  be  of 
the  carbonate  type  and  would  dissolve  calcium  carbonate  as  well  as  fluorite, 
with  the  probability  that  low-temperature  deposition  of  both  minerals  would 
take  place  simultaneously  when  the  waters  issued  into  fissures. 

E.  0.  Ulrich  and  W.  S.  Tangier  Smith  reported  on  the  fluorspar  deposits 
of  western  Kentucky  in  1905,  and  remarked  on  the  general  similarity  of  these 
with  the  southern  Illinois  veins.4  Smith  herein  expresses  belief  in  the  theory 
that  the  fluorspar  and  ore  minerals  were  leached  from  deep-lying  limestones 
by  rising  thermal  solutions  and  that  they  were  deposited  in  the  upper  zones 

1  For  the  origin  of  the  zinc-lead  deposits  of  the  Joplin  region  see  the  clear  and  con- 
vincing exposition  by  C.  E.  Siebenthal  in  U.  S.  Geol.  Survey  Bull.  606,  1915  ;  on  the 
southwest  Wisconsin  area,  by  U.  S.  Grant,  Wisconsin  Geol.  and  Nat.  Hist.  Surv.,  Bull. 
14,  1906,  in  which  he  states  the  meteoric  origin  and  its  relation  to  structural  basins 
having  an  impervious  stratum  along  which  seeping  and  circulating  waters  were  deflected 
and  directed. 

2  Editor's  note.  Attention  is  called  to  a  paper  describing  a  Wisconsin  occurrence  of 
nuorite  in  association  with  calcite,  pyrite,  and  galena,  which  apparently  is  related  neither 
to  taulting  nor  to  igneous  activity.  Bagg,  Rufus  Mather,  Fluorspar  in  the  Ordovician 
iimestone  of  Wisconsin:  Bull,  of  the  Geol.  Soc.  of  America,  Vol.  29,  pp.  393-398,  1918. 
91  10™  mo™'  S-  F"  FluorsPar  deposits  of  southern  Illinois:  Am.  Inst.  Min.  Eng.,  Vol. 
*1,   la\)Z,  p.    52. 

4  Ulrich,  E.  O.,  and  Tangier  Smith,  W.  S.,  The  lead,  zinc,  and  fluorspar  deposits  of 
western  Kentucky:     Prof.   Paper  36,  U.  S.  Geol.   Surv..   1905,  p.   15  and  p.   150. 


276  GEOLOGY    OF    HARDIN    COUNTY 

of  fissures  where  decreases  of  temperature  and  of  pressure  caused  precipita- 
tion. To  quote  from  pages  150  and  151  of  Smith's  paper,  "The  intimate 
association  of  the  fluorite  with  other  minerals  known  to  have  been  deposited 
from  solution,  the  fact  that  it  is  known  to  be  somewhat  soluble  both  in  pure 
water  and  in  ordinary  surface  and  underground  waters,  and  to  have  been 
actually  deposited  from  such  waters,  and  the  fact  that  the  fluorite  in  the  veins 
is  generally  sharply  limited  by  the  fissure  walls,  which,  except  for  the  effects 
of  recent  surface  waters,  show  no  corrosion  or  other  action  such  as  might  be 
caused  by  fluorine  gas  or  molten  fluorite,  would  seem  to  render  it  unneces- 
sary to  consider  further  any  other  mode  of  deposition  than  that  from  circu- 
lating underground  waters."  Regarding  these  points,  the  writer  feels  that 
he  can  not  remark  on  the  correctness  of  Smith's  statements  as  applied  to  the 
Kentucky  deposits,  but  he  can  not  feel  that  the  Illinois  deposits  substantiate 
the  ideas  quoted  above.  In  the  first  place,  Smith's  first  point  "*  *  *  asso- 
ciation with  other  minerals  known  to  have  been  deposited  from  solution,"  has 
no  significance.  He  does  not  state  that  these  particular  associated  minerals 
are  always  precipitated  from  one  type  of  solution.  As  a  matter  of  fact,  the 
'•'other  minerals"  have  been  known  to  be  deposited  from  solutions  of  several 
types  and  origins.  Commenting  on  the  next  point — "that  it  (fluorite)  is 
known  to  be  somewhat  soluble  both  in  pure  water  and  in  ordinary  surface 
waters  and  to  have  been  actually  deposited  from  such  waters,"  the  writer 
believes  in  the  truth  of  these  statements,  but  is  unable  to  agree  that  this  point 
also  "would  seem  to  render  it  unnecessary  to  consider  further  any  other  mode 
of  deposition  than  that  from  circulating  underground  waters."  The  thing  to 
be  accounted  for  is  not  the  presence  of  fluorine — such  as  might  admittedly  be 
precipitated  from  cold  meteoric  waters — but  the  unusual  concentration  of  the 
substance.  For  further  comment  on  Smith's  statements  when  applied  to  the 
Illinois  veins,  instead  of  a  lack  of  corrosive  or  other  strong  action  being 
suggested,  the  writer  considers  the  very  strong  replacement  relationships  of 
the  veins  and  the  complexity  of  boundaries — sometimes  almost  impossible  to 
define — between  the  fluorite  and  the  calcite  or  wall  rocks  as  being  of  precisely 
opposite  significance,  namely,  that  strong  action  most  certainly  is  suggested 
by  the  textures  and  structures  of  the  veins.  Smith  gives  several  analyses  to 
show  that  limestones  of  the  region  contain  an  appreciable  amount  of  fluorine, 
the  highest  analysis  quoted  showing  0.10  per  cent  fluorine.  This  fluorine  may, 
however,  have  been  subsequently  introduced  into  the  limestone  as  a  result  of 
circulating  waters  obtaining  their  content  from  the  deposits,  or  from  the  same 
source  as  the  veins.  Finally,  if  circulating  ground  waters  concentrated  the 
fluorspar,  why  were  not  more  of  the  more  superficial  fissures  given  an  appreci- 
able amount  of  fluorite  ? 

After  a  detailed  study  of  the  Illinois  fluorspar  regions  in  1904,  Bain1 
believed  "that  the  evidence  points  to  heated  waters  having  been  the  agency 

1  Bain,  H.  Foster,  The  fluorspar  deposits  of  southern  Illinois :     U.  S.  Geol.  Surv.  Bull. 
255,   1905. 


ECONOMIC    GEOLOGY  277 

by  which  the  ores  were  segregated  and  that  they  obtained  an  essential  portion 
of  their  load  from  a  larger  mass  of  lower-lying  intruded  rock  of  which  the 
dikes  are  now  offshoots."  As  to  whether  the  depositing  waters  were  of 
magmatic  origin,  or  whether  they  were  meteoric  and  derived  their  fluorine 
content  from  magmatic  emanations  at  depth,  Bain  does  not  make  a  final 
decision,  but  he  does  not  favor  the  view  that  they  dissolved  disseminated 
fluorite  from  the  limestones.  As  he  states,  "*  *  *  it  may  be  pointed 
out  that  the  normal  tendency  of  heated  waters  rising  along  faulting  fissures 
would  undoubtedly  be  toward  deposition  and  dissemination  of  material  rather 
than  toward  its  segregation.*'  This  would  be  especially  true  if  the  mineral 
content  of  these  waters  was  distinctly  less  soluble  under  given  conditions  than 
other  mineral  substances  that  would  be  encountered  along  the  line  of  travel, 
which  is  in  reality  the  relationship  between  fluorite  on  the  one  hand  and  cal- 
cite  on  the  other.  Finally,  Bain  remarks,  "The  association  of  the  minerals 
and  the  common  phenomena  of  marked  silicification  of  the  hanging  wall  are 
interpreted  as  indicating  deposition  from  heated  ascending  solutions  carrying 
fluosilicates  of  zinc,  lead,  copper,  iron,  barium,  and  calcium.  These  are  be- 
lieved to  have  been  broken  up  and  precipitated  by  descending  cold  waters, 
which  possibly  also  furnished  the  sulphur  to  combine  with  the  metals,  though 
it  is  not  improbable  that  sulphur  was  an  original  constituent  of  the  rising 
solutions." 

In  a  later  study  of  the  Kentucky  deposits,  Fobs1  assigns  the  deposits  to 
the  ^'thermo-aqueous''  genetic  class,  and  considers  the  fluorspar  as  being 
derived  from  silicofluorides  of  various  metals  which  reacted  with  calcium 
bicarbonate  to  form  CaF2.  Such  reaction  would  also  cause  the  formation  of 
silica,  barium  sulphate,  and  metallic  sulphides,  the  sulphur  coming  from 
postulated  hydrogen  sulphide.  In  this  case,  however,  we  might  expect  to  find 
evidences  of  contemporaneity  among  all  the  vein  minerals  rather  than  the 
definite  sequence  which  has  been  previously  described  in  this  paper.  Fohs 
further  speaks  of  the  lack  of  sufficient  fluorine  in  the  wall  rocks  to  form 
CaF2,  and  suggests  a  parent  magma — of  which  the  dikes  are  apophyses — as 
the  likely  source  of  the  fluorine.  This  element  was  "brought  up  in  thermal 
solutions  as  an  after  effect  of  the  eruption."  Thus  Fohs  ascribes  a  direct- 
igneous  origin  for  the  fluorite  and  metallic  sulphides. 

Siebenthal2  alludes  to  the  Kentucky-Illinois  district  in  connection  with 
his  study  of  zinc-lead  areas,  and  calls  attention  to  structural  features  favoring 
an  origin  similar  to  that  imputed  to  the  Joplin  ores,  apparently  seeing  no 
significance  in  the  many  localized  faults,  the  igneous  rocks,  the  great  develop- 
ment of  fluorite,  and  the  argentiferous  quality  of  the  galena.     These  four 

1  Fohs,  F.  J.,  Fluorspar  deposits  of  Kentucky:  Kentucky  Geological  Survey  Bull.  9, 
pp.  61-63.  1907.  The  fluorspar,  lead,  and  zinc  deposits  of  western  Kentucky:  Econ. 
Geol..  Vol.   V.    pp.    377-386.    1910. 

2  Siebenthal,  C.  E.,  Origin  of  the  zinc  and  lead  deposits  of  the  Joplin  region,  Missouri, 
Kansas  and   Oklahoma:     U.   S.   Geol.   Survey  Bull.   606,  pp.    213-217.    1915. 


278  GEOLOGY    OF    HARDIN    COUNTY 

characteristics  are  distinctly  the  reverse  of  conditions  in  the  Missouri  lead- 
zinc  districts  which  comprise  the  subject  of  Siebenthal's  paper.  Moreover,  he 
apparently  regards  as  mere  coincidences  the  fault-fissure  fluorite  veins  of 
Durham  and  Derbyshire,  England,  which  are  said  to  have  mineral  associations 
and  structures  similar  to  the  Illinois  veins,  and  which  are,  according  to  Bain, 
situated  in  limestones  of  about  the  same  age,  in  which  very  similar  basic 
dikes  are  present.  By  no  means  is  this  evidence  conclusive  regarding  any  mode 
of  origin  for  the  Illinois  veins,  but  it  should  be  considered  as  suggestive. 
The  veins  of  fluorspar  near  Freiburg  (according  to  Bain)  occur  in  gneisses, 
schists,  and  slates,  but  these  rocks  are  likewise  traversed  by  dikes  of  gabbro 
besides  some  dikes  of  quartz  porphyry,  and  the  galena  of  the  veins  is  argenti- 
ferous. Commenting  on  Siebenthal's  statement  of  similarity  in  the  structure 
of  the  Joplin  and  the  Kentucky-Illinois  regions,  it  seems  to  the  writer  more 
significant  to  point  out  the  great  dissemilarities  in  structure  of  the  ore  bodies, 
as  well  as  the  extreme  faulting  of  the  Illinois  region  which  is  certainly  not 
true  of  the  Joplin  area.  Thus  the  two  regions  present  great  contrasts  in  some 
of  those  geologic  phenomena  which  are  among  the  most  important  to  consider 
in  the  solution  of  an  ore  genesis  problem. 

SUMMARY   OF  GENETIC  EVIDENCE 

The  evidence  bearing  upon  the  genesis  of  the  Hardin  County  deposits 
appears  throughout  the  descriptive  matter  of  this  paper.  It  may  be  sum- 
marized as  follows : 

1.  The  enormous  mass  and  notable  concentration  of  fluorite,  a  mineral 
carrying  48.9  per  cent  of  fluorine  (when  pure),  which  is  a  normal  product  of 
igneous  activity,  and  in  concentrated  condition  especially  the  result  of  mag- 
matic  differentiation. 

2.  The  presence  of  basic  igneous  dikes  and  sills,  and  of  fragmental 
acidic  igneous  material  which  may  be  explosive  products  of  vulcanism.  These 
opposite  chemical  types  of  igneous  rock  in  the  same  province  make  possible 
the  postulation  of  magmatic  differentiation  at  depth,  and  indicate  that  the 
region  was  one  of  more  or  less  pronounced  igneous  activity,  that  is,  it  overlies 
a  mass  of  igneous  rock  of  which  the  dikes,  etc.,  are  offshoots.  The  proximity 
of  a  large  igneous  intrusion  is  also  suggested  by  a  slight  doming  of  the  strata 
and  the  complex  pattern  of  mosaic  block  faulting. 

3.  The  presence  in  the  igneous  rock  of  conspicuous  quantities  of  apatite, 
phlogopite,  and  biotite,  the  first  two  of  which  especially  are  usually  fluorine- 
bearing  minerals.  These  facts  indicate  that  the  parent  magma  held  a  fluorine 
content  and  the  point  is  further  sustained  by  the  analysis  of  the  Mix  dike 
near  Golconda  which  shows  0.13  per  cent  of  fluorine.1  In  connection  with  this 
investigation,  no  analyses  were  made,  however. 

1  Analysis  by  George   Steiger,   U.   S.   Geol.    Surv.,   quoted  from  Bain's  report,   op.   cit. 


ECONOMIC    GEOLOGY  279 

4.  The  presence  of  extensive  faults,  some  of  which  are  evidently  deep- 
reaching,  within  the  largest  of  which  the  bulk  of  the  fluorspar  occurs  and  in 
possible  connection  with  which  the  fluorspar  is  almost  exclusively  found. 

5.  The  absence  of  fluorite  from  many  faults.  This  militates  strongly 
against  an  origin  as  a  result  of  laterally  flowing  solutions. 

6.  Association  with  sphalerite,  argentiferous  galena,  pvrite,  chalco- 
pyrite,  and  possibly  stibnite,  introduced  after  the  chief  period  of  fluorspar 
deposition,  and  suggesting  a  stage  in  an  active  mineralizing  period.  A  suc- 
cession of  mineralizing  stages  and  this  general  association  of  minerals  seem 
to  be  very  common  phenomena  of  ore  deposits  formed  by  solutions  which  have 
direct  connections  with  igneous  activity. 

7.  The  conspicuous  and  unmistakable  replacement  of  calcite  by  fluor- 
spar in  amount  and  manner  suggesting  an  intense  period  of  mineralizing 
action. 

8.  The  occurrence  of  fluorspar-calcite  veins  within  and  bordering  the 
igneous  dike  at  Orrs  Landing. 

9.  The  relative  insolubility  of  fluorspar  as  contrasted  with  calcium 
carbonate,  rendering  difficult  the  gathering  of  disseminated  fluorspar  from 
widespread  areas  through  the  agency  of  circulating  ground  waters. 

These  points  are  thought  to  weigh  heavily  in  favor  of  an  igneous  origin 
as  opposed  to  a  concentration  by  waters  from  the  surrounding  sediments. 
Thus  he  is  in  accord,  in  general,  with  Fohs'  idea  of  origin,  though  nowhere 
in  the  literature  studied  does  Fohs  seem  to  marshal  sufficient  evidences  to 
warrant  his  conclusion.  The  evidences  submitted  above  are  those  of  the 
writer's  observations  and  seem  to  him  far  more  greatly  to  substantiate  the 
theory  that  thermo-aqueous  solutions  which  emanated  directly  from  a  large 
igneous  intrusion  at  depths  ascended  along  deep-reaching  fissures — probably 
developed  mostly  by  igneous  disturbance — and  deposited  their  solutes  in  upper 
zones  where  decrease  of  temperature  and  pressure  (aided  by  the  chemical 
character  of  the  rocks)  caused  precipitation. 

CHEMICAL   CONSIDERATIONS 

As  to  the  chemical  condition  of  the  fluorine  brought  up  by  the  ascend- 
ing waters,  the  writer  feels  that  sufficient  evidence  is  not  at  hand  to  warrant 
a  final  decision.  Fluorine  gas  may  have  been  the  chief  solute.  In  case,  how- 
ever, silica  was  also  a  solute — as  it  often  is  in  magmatic  waters — silicon 
fluoride  would  probably  have  formed  according  to  the  reactions : 

2F2-f2H20=4HF+02  (1) 

Si02+4HF=SiF4+2H20  (2) 

and  the  silicon  fluoride  reacting  with  CaCO:; ; 

SiF4+2CaC03=Si02+2C02+2CaF2  (3) 


280  GEOLOGY    OF    HARDIN    COUNTY 

In  the  absence  of  silica,  the  hydrogen  fluoride  (formed  according  to  equation 
1 )  would  react  directly  with  calcium  carbonate : 

2HF+CaC08=CaF2+H20+C02  (4) 

The  calcium  carbonate  would  be  encountered  (as  limestone)  along  the  path 
of  the  ascending  waters.  If  reaction  (3)  had  taken  place  we  should  expect 
to  find  a  contemporaneous  deposition  of  quartz  and  fluorite.  The  veins,  how- 
ever, contain  very  large  aggregations  of  pure  fluorite,  instead  of  an  inter- 
growth  of  that  mineral  with  quartz.  Some  parts  of  the  bedding  deposits 
(relatively  of  very  subordinate  amount)  might  support  this  condition.  If 
the  magma  had  differentiated  at  depth  into  basic  and  acidic  portions,  the 
fluorine  becoming  concentrated  in  the  acidic  split,  magmatic  emanations 
would  very  likely  have  carried  silica.  Differentiation  of  the  magma  is  sug- 
gested by  the  two  types  of  igneous  phenomena  in  the  district,  namely,  the 
basic  dikes  and  the  acidic  volcanic  breccias,  and  also  by  the  veinlet  of 
fluorspar  which  cuts  the  dike  at  Orrs  Landing.  The  fluorspar  here  is  plainly 
subsequent  to  the  igneous  rock. 

The  emanation  of  fluorine  from  a  basic  magma  would  not  have  been 
accompanied  by  much  silica,  unless  the  fluorine  itself  were  responsible  for 
an  impoverishment  of  the  original  magma  with  respect  to  silica  content.  In 
such  a  case,  we  might  expect  very  unusual  types  of  basic  rocks  to  result  by 
subsequent  magmatic  intrusion.  The  igneous  rocks  of  Hardin  County  are 
indeed  somewhat  extraordinary  in  the  marked  development  of  apatite  and 
the  micas.  The  latter,  especially,  occur  more  commonly  in  normal  acidic  or 
intermediate  rocks  than  in  such  extremely  basic  types.  In  this  connection 
should  be  considered  Fohs'  statement  that  the  Kentucky  dikes  average  only 
34  per  cent  Si02,  an  amount  which  is  sufficient  to  form  only  orthosilicate 
minerals.  If,  on  the  other  hand,  the  original  magma  never  had  other  than 
a  relatively  basic  composition,  fluorine  or  hydrogen  fluoride  emanating  there- 
from would  react  directly  with  calcium  carbonate  along  the  path  and  wonld 
have  formed  fluorite  without  any  contemporaneous  deposition  of  quartz. 
This  condition  would  be  given  plausibility  if  one  could  prove  that  the  basic 
dikes  and  the  acidic  breccias  are  not  directly  consanguineous  in  origin.  Field 
data  neither  prove  nor  disprove  this. 

Another  suggestion  is  that  calcium  fluoride  was  a  constituent  of  the 
magma  and  emanated  as  such.  This  mineral  does  not  appear  in  any  of  the 
igneous  rock  sections  studied,  but  the  rocks  are  all  considerably  altered  to 
calcite  and  thus  small  amounts  of  calcium  fluoride  might  have  been  com- 
pletely changed  in  this  direction.  Fluorite  is  said  to  be  altered  to  calcite  by 
the  action  of  percolating  bicarbonate  waters.1 

Finally,  Fohs  and  others  mention  the  possibility  that  the  ascending 
waters  carried  fiuosilicates  of  the  various  metals,  especially  of  iron,  lead,  zinc, 

1  F.   W.  Clark,   Data  of  geochemistry,   U.   S.   Geol.    Surv.   Bull.    616,   1916,   p.    336. 


ECONOMIC    GEOLOGY  281 

and  copper,  and  that  fluorite  was  deposited  as  the  result  of  interaction  between 
these  compounds  and  calcite.  This  does  not  seem  to  be  supported  to  any 
appreciable  extent  by  the  paragenetic  relationships  between  the  vein  minerals. 
If  such  compounds  were  the  source  of  fluorine  in  the  veins  we  should  expect 
much  contemporaneity  of  fluorite  and  sulphides  to  be  indicated,  especially 
in  the  direction  of  much  dissemination  of  sulphides  of  the  metals  through- 
out the  fluorite  masses.  We  may  very  likely  thus  account  for  the  small 
amounts  of  disseminated  metallic  sulphide  that  we  And,  but  not  for  the  larger 
sulphide  masses. 

A  detailed  study  of  the  chemistry  of  fluoriferous  solutions  was  not 
possible  in  connection  with  the  preparation  of  this  paper,  but  the  writer 
believes  that  the  geochemical  problems  involved  in  the  genesis  of  the  fluorite 
veins  are  worthy  of  special  investigations. 

GEOLOGIC    HISTOEY   OF    THE   DEPOSITS 

The  evidence  given  throughout  the  paper  points  to  a  sequence  of  events 
roughly  as  follows : 

The  region  was  subjected,  in  post-Pottsville,  probably  post-Carboniferous 
times,  to  a  period  of  upbowing  followed  by  normal  faulting.  The  localized 
geographic  situation  and  character  of  these  deformations  suggest  a  deep- 
lying  adjustment  of  a  magma,  the  presence  of  which  is  manifested  in  the 
occurrence  of  several  igneous  rock  exposures.  During  the  following  period 
of  major  faulting,  calcite  was  developed  as  a  fissure  filling  either  by  direct 
precipitation  from  circulating  waters,  or  by  some  recrystallization  of  lime- 
stone fragments  caught  in  the  grinding  movement  along  the  fault  planes.  In 
the  latter  case,  the  fault  zones  loosely  filled  with  calcite  would  afford  easy 
access  to  solutions  containing  fluorine  and  favorable  conditions  and  material 
for  the  deposition  of  their  load.  In  the  former  case,  the  calcite-filled  veins 
would  in  many  cases  prove  to  be  the  relatively  weak  zones  along  which  subse- 
quent Assuring  would  more  easily  take  place  during  the  later  stages  of  fault- 
ing, and  so  also  would  provide  favorable  paths  for  ascending  solutions.  The 
fluoriferous  thermal  solutions,  leaving  the  magma  during  its  differentiation 
and  cooling,  followed  upward  along  the  deeper-reaching  fault  fissures,  and 
upon  cooling  and  decrease  of  pressure  attained  in  the  upper  sediments,  began 
a  process  of  mineral  deposition.  Thus  great  bodies  of  fluorspar  were  formed, 
replacing  the  calcite  of  the  veins  or  the  limestone  of  the  walls.  In  the  later 
course  of  the  deposition,  though  scarcely  separated  from  the  earlier  by  time 
interval,  the  uprising  solutions  changed  somewhat  in  composition,  bringing 
material  for  the  formation  of  metallic  sulphides  which  were  thus  introduced 
into  veins  already  largely  filled  with  fluorspar,  and  especially  along  shear 
zones  in  the  fluorspar  mass.  This  was  the  terminating  main  feature  of  the 
mineralization  period  which  was  probably  relatively  short  and  intense.     Sub- 


282  GEOLOGY    OF    HARDIN    COUNTY 

sequently,  prolonged  weathering  and  erosion,  and  minor  faulting,  brought  the 
surface  down  to  the  zone  of  vein  formation,  thus  exposing  the'  deposits  to 
discovery  and  exploitation. 

MINING   AND   MILLING   METHODS 
MINING 

Veins. — In  exploiting  a  vein  the  shaft  is  generally  sunk  in  the  hanging 
wall  if  the  vein  hades  appreciably,  and  in  the  foot-wall  if  the  vein  is  prac- 
tically vertical.  Levels  are  established  usually  at  100  foot  intervals,  though 
in  the  earlier  days  the  intervals  were  smaller.  Cross-cuts  are  driven  from  the 
shafts  to  the  vein,  and  drifts  are  then  driven  on  the  vein  in  both  directions. 
This  is  the  method  of  opening  employed  in  all  the  recent  developments,  but 
in  the  case  of  the  old  Good  Hope  shaft,  sinking  followed  the  vein  matter  as  a 
steep  incline. 

Overhand  stoping  methods  are  usually  employed,  except  in  a  few  cases 
where  exceptionally  rich  vein  matter  makes  it  desirable  to  remove  material 
at  the  drift  floor  by  underhand  stoping.  Overhand  stopes  are  worked  within 
15  to  25  feet  of  the  upper  level,  leaving  this  amount  to  supply  supporting 
pillars  and  tunnel  floors.  In  a  few  instances  all  material  has  been  removed 
between  levels  for  a  short  distance,  necessitating  a  bridging  of  the  upper 
drift. 

The  walls  are  generally  very  firm  and  require  little  timbering.  In  some 
places,  however,  where  the  faulting  has  resulted  in  a  wide  fracture  zone 
instead  of  a  single  break,  some  difficulty  is  encountered. 

One  of  the  greatest  mining  difficulties  met  with  is  in  dealing  with  so- 
called  "mud-runs/7  Large  solution  cavities  in  the  limestone  walls,  especially 
near  the  upper  levels,  become  filled  with  mud  by  infiltration.  Where  these 
adjoin  the  veins,  they  are  apt  to  be  tapped  in  the  process  of  developing  the 
stopes  or  drifts,  with  the  result  that  great  quantities  of  a  thin  clay  mud  may 
flow  out  with  disconcerting  results.  Once  a  reservoir  is  thus  tapped,  nothing 
may  be  done  but  to  allow  it  to  drain  and  to  remove  the  slime  at  great  expense. 
Probably  only  at  prohibitive  expense  could  these  mud  reservoirs  be  located 
in  advance  and  avoided. 

Superficial  deposits. — The  superficial  or  "gravel  spar"  deposits  are  mined 
by  open-cut  methods  to  depths  usually  less  than  twenty  feet,  requiring  merely 
the  loosening  and  removal  of  the  materials  by  pick  and  shovel,  and  washing 
to  remove  the  adhering  clay.  This  simple  form  of  mining  is  obviously  rela- 
tively inexpensive,  but  is  applicable  only  to  shallow  depths.  It  may  be 
economically  applied  to  prospects  in  proving  the  existence  of  a  vein.  The 
Pierce  mines  north  of  Golconda  probably  afford  the  best  example  of  successful 
pit  mining  in  the  district,  and  the  distribution  of  the  workings  clearly  out- 
lines the  courses  of  the  veins  (see  figure  21). 


ECONOMIC    GEOLOGY 


283 


Bedding  deposits. — In  mining  the  bedding  deposits,  such  as  those  at 
Lead  Hill,  tunnels  are  driven  from  one  or  more  points  on  the  hillside  and  a 
somewhat  irregular  room-and-pillar  method  of  development  is  followed. 
Since  the  strata  are  practically  horizontal  and  usually  not  over  two  or  three 
feet  in  thickness,  little  difficulty  is  encountered,  providing  care  is  taken  to 
leave  adequate  pillars  for  support.  Little  timbering  is  used.  Apparently  no 
attempt  is  made  to  develop  rooms  and  pillars  of  uniform  size  and  spacing  on 
account  of  the  irregular  outlines  of  the  ore-bodies,  and  their  insufficient  lateral 
extent. 

MILLING    METHODS 

General. — For  the  concentration  of  the  fluorspar  and  the  metallic 
minerals  mined  from  veins  or  bedding  deposits,  coarse  breaking,  hand  sorting, 


Fig.  23. — Mill  and  Good  Hope  shaft  of  the  Fairview  Fluorspar  and  Lead  Company. 


crushing,  and  jigging  in  Joplin  jigs,  comprise  the  usual  method.  Where 
blende  is  absent  from  the  galena-fluorspar-calcite  ore,  very  little  difficulty  is 
experienced,  except  that  since  the  jigs  make  only  two  products,  the  tailings 
will  contain  all  the  fluorspar  and  calcite  together.  This  mixture  is  sold  as 
low  grade  "gravel  spar."  This  gravel  spar,  it  will  be  seen,  is  an  entirely 
different  product  from  the  residual  gravel  spar  of  the  superficial  deposits,  and 
the  two  should  not  be  confused. 

If  both  blende  and  galena  occur  in  the  ore,  considerable  difficulty  is 
encountered  in  concentrating.  The  jig  is  not  applicable  to  the  mixture,  for 
although  a  galena  concentrate  of  good  quality  can  be  obtained,  the  valuable 
fluorspar  product  will  be  contaminated  by  the  zinc  mineral.     The  practice  is 


284 


GEOLOGY  OF  HARDIN  COUNTY 


to  direct  all  zinc-bearing  materials  to  a  separate  part  of  the  mill  for  finer 
crushing  and  treatment  on  tables.  Such  material — usually  a  blende-galena- 
fluorspar-calcite  mixture — also  presents  difficulties  on  the  tables,  it  being 
generally  impossible  to  effect  separation  of  all  the  minerals.  The  galena  may 
be  separated  almost  completely,  but  the  similarity  of  specific  gravities  of 
fluorspar  and  blende,  and  the  dissemination  of  the  latter  tend  to  give  a 
middling  product  containing  both;  a  clean  product  is  therefore  unobtainable 
except  by  secondary  and  expensive  installations.  The  solution  of  the  problem 
of  economic  recovery  probably  depends  upon  the  application  of  selective 
flotation  methods,  along  which  line  experiments  have  been  made.  At  the 
time  of  this  investigation  the  zinciferous  products  had  been  thrown  out  as 
waste  or  set  aside  for  experimentation. 


Fig.  24. — Mill  and  Rosiclare  mine  of  the  Rosiclare  Lead  and  Fluorspar  Company. 


In  places  where  the  sulphide  minerals  do  not  accompany  the  fluorspar, 
jigging  with  close  adjustment  and  careful  operation,  effects  a  fair  separation 
between  the  spar  and  calcite  or  limestone,  although  the  minerals  differ  but 
about  0.4  in  specific  gravity.  Where  quartz  is  present  it  will  be  found  in  the 
calcite  tailing,  unless  it  is  intimately  intergrown  with  the  fluorspar,  when  it 
will  contaminate  this  product. 

The  superficial,  or  gravel-spar,  deposits  where  the  fluorspar  is  embedded 
in  residual  clays,  contain  no  other  minerals,  and  require  therefore  only  a 
thorough  washing  to  remove  the  clay  that  adheres  to  the  spar.  This  washing 
is  done  by  trommels,  log  washers,  or  concrete  mixers. 


ECONOMIC    GEOLOGY 


285 


Fairview  Mill. — The  output  of  all  the  Fairview  Fluorspar  and  Lead  Com- 
pany's mines  passes  through  the  Fairview  mill  located  at  the  Good  Hope 
shaft  (fig.  23).  In  this  mill  the  lumps  of  pure  fluorspar  are  hand-sorted  from 
the  picking  belt  as  first  and  second  grade  lump  spars.  The  whitest  is  the 
purest,  and  is  known  as  Keystone,  a  very  high-grade  "acid  spar."  All  zinc- 
bearing  material,  part,  of  which  contains  lead,  is  crushed  by  rolls  to  sufficient 
fineness  for  treatment  on  Deister  tables,  from  which  is  obtained  a  marketable 
lead  concentrate,  a  zinc-bearing  middling  containing  much  fluorspar  and  some 
lead,  and  a  fluorspar-calcite  tailing.  All  lead-bearing  rock  containing  no 
zinc  is  removed  from  the  hand-picking  belt  to  a  separate  bin,  from  which  it 
goes  to  rolls,  is  screened,  and  sent  to  Joplin  jigs ;  the  products  of  these  opera- 
tions are  a  lead  concentrate,  and  a  "gravel  spar"  tailing  of  fluorspar  and 
calcite.     A  generalized  flow-sheet  of  the  mill  follows : 


Ore  from  mine 

1 

1 

Washing  trommel 

1 

1 
Hand  picking  belt 

1 

1 

Lead-spar-calcite 
material 

1 

Zinc-bearing 
material 

Fluorspar 

! 

1 

i 

i 
4  grades 

Rolls 
toi 

Joplir 

and  screen 
'  size 

i  jigs 

Rolls  i"  (?) 

1 

Deister  tables 

—Keystone 
(lump) 
—  Al  ground 
— A2  lump 
—gravel 

1 
Lead 
concentrate 

1 

Zinc-fluorspar 
mixture 

Fluor-spar 
tailing 

1 

Calcite 

tailing 

Market 

1 
(Flotation) 

1 

(Market) 

Cleaned 

1 

Market 

1 

Lead 
cone 

;entrate 

1 

Gravel 
spar 

Market 


Market 


Rosiclare  Mill. — The  mill  of  the  Rosiclare  Lead  and  Fluorspar  Company 
is  located  at  the  main  shaft  of  the  Eosiclare  mine  (fig.  24)  and  receives  all 
material  mined  on  the  company's  properties.  The  operations  are  funda- 
mentally similar  to  those  of  the  Fairview  mill  but  differ  in  a  few  details. 

No  attempt  is  made  to  save  the  small  amount  of  zinc. 


286 


GEOLOGY    OF    HARDIN    COUNTY 


An  interesting  feature  of  the  flow-sheet  which  follows  is  the  use  of  a 
small  Kichards'  pulsator  jig  for  cleaning  all  the  lead  concentrates  of  the 
Joplin  jigs.     The  flow-sheet  given  here  is  abridged  and  generalized. 


Ore  from  mine 

I 

Sorting  belt 


Acid  spar" 
(may  be  ground,  or 
marketed  as  lump) 


Second  grade  spar 
(lump  or  ground) 


Lead-bearing 
material 


Gyratory  crusher 

I 

Disc  crusher 

I 

Trommel  (¥—$") 


Oversize 


Middle  size 
G"-i") 


Jig. 


Undersize 
tt"-0) 


Jig 


Lead  concentrate 


Lead  concentrate 


Rolls  i" 


Low-grade 
spar 


Market 


Tailings 


Richards'  pulsator  jig 
(for  cleaning) 


Lead  concentrate 
Market 


TailiDgs 


.Table 


Lead  concentrate 


Market 


Middling 

I 

Crusher 


Spar 
Market 


Tailing 
Waste 


At  the  mill  of  the  Lee  mine,  a  simple  arrangement  of  sizing  and  jigging 
was  practised,  as  outlined  below.  This  type  of  mill  is  suitable  for  small 
mines  where  the  product  contains  but  two  minerals  differing  appreciably  in 
specific  gravity.  Here  the  separation  of  calcite  (limestone)  and  fluorspar  is 
quite  readily  attained.  The  product  of  the  Lee  mine  contains  neither  lead 
nor  zinc  minerals.     The  mill  flow-sheet  is  essentially  as  follows: 


ECONOMIC   GEOLOGY 


287 


Ore  from  mine 

1 

1 
Rolls  (25  mm.) 

Trommel 
(12  mm.) 

1 

1 

Oversize 

1 

Undersize 

1 

Jig  1 

1 

1 
Trommel 
(4  mm.) 

1 

1 

Concentrate 

Tailing 

1 

Oversize 
(12  mm.  to  4  mm.) 

1 

Jig  2 

1 

Undersize 
(under  4  mm.) 

1 

Trommel  (1^  mm.) 

1 

Concentrate 

1          1 

Tailing               Oversize 
(4  mm. 

1 

Jiff  3 

1 

to  U 

i  mm.) 

1 

Undersize 
(Under  1|  mm.) 

1 

Jig  4 

Concentrate  Tailing  Concentrate  Tailing 

Other  mills  closely  correspond  to  one  or  another  of  the  types  described 
above. 

ECONOMIC    CONSIDERATIONS 

Fluorspar  and  the  chemical  products  made  from  this  mineral,  possess  a 
wide  variety  of  uses.  The  value  of  fluorspar  is  due  to  three  qualities:  to  its 
fluxing  properties,  which  give  it  a  place  in  certain  important  metallurgical 
operations  and  in  the  manufacture  of  glazes;  to  its  fluorine  content,  which 
renders  it  the  chief  raw  material  for  the  manufacture  of  fluorine  compounds 
employed  in  various  chemical  industries,  especially  for  hydrofluoric  acid; 
and  to  its  optical  properties,  which  invest  clear  specimens  with  a  specialized 
application  in  making  lenses  for  microscopes. 

About  four-fifths  of  the  fluorspar  produced  in  the  United  States  is  con- 
sumed as  a  flux  in  the  production  of  steel  by  the  basic  open-hearth  process. 
For  this  purpose,  the  fluorspar  should  contain  less  than  10%  of  impurities, 
except  that  calcite  which  is  frequently  present  is  not  objectionable  and  may 
run  higher.  Silica  should  preferably  be  less  than  2  per  cent,  though  the 
spar  may  contain  up  to  4  per  cent,1  This  flux  is  used  principally  for  giving 
fluidity  to  slags  that  are  too  viscous,  but  at  the  same  time  it  facilitates  the 
passage  of  impurities  such  as  sulphur  and  phosphorus  into  the  slag.  The 
consumption  of  fluorspar  per  ton  of  steel  produced  in  this  way  varies  from 
4  to  17  pounds,  with  8  pounds  as  a  fair  average.1    On  this  basis  the  1916  pro- 

1  This  statement  is  made  on  the  basis  of  the  purity  of  commercial  gravel  spar. 


288  GEOLOGY    OF    HARDIN    COUNTY 

duction  of  basic  open-hearth  steel  amounting  to  29,600,000  tons  is  estimated 
to  have  consumed  about  120,000  tons  of  fluorspar.1 

The  bulk  of  the  fluorspar  not  consumed  by  the  steel  industry  is  devoted 
to  the  manufacture  of  ceramic  products,  such  as  enameled  and  sanitary  ware, 
opalescent  glass,  facing  for  bricks,  and  vitriolite,  and  to  the  manufacture 
of  hydrofluoric  acid.  For  both  purposes  fluorspar  of  a  high  degree  of  purity 
is  required.  In  the  manufacture  of  hydrofluoric  acid  the  fluorspar  is  treated 
with  sulphuric  acid,  and  in  the  process  the  presence  of  impurities  in  the  fluor- 
spar, such  as  calcium  carbonate  and  silica,  are  very  detrimental.  The  calcium 
carbonate  neutralizes  sulphuric  acid,  and  its  presence  to  the  extent  of  1  per 
cent  or  over  causes  considerable  foaming  upon  mixing.  Silica,  if  present, 
forms  hydrofluosilicic  acid  in  such  proportion  that  for  every  part  of  silica 
nearly  four  parts  of  fluorspar,  and  more  than  five  parts  of  sulphuric  acid  of 
66°  Baume  are  wasted,  since  for  practically  all  applications  of  hydrofluoric 
acid  the  content  of  hydrofluorsilicic  acid  is  useless.  Thus  for  every  per  cent 
of  silica  in  fluorspar,  ten  per  cent  should  be  deducted  from  the  value  of  the 
fluorspar.2  Hydrofluoric  acid  finds  a  varied  use  as  a  chemical  agent  and  is 
enjoying  a  growing  application  in  the  production  of  aluminum  fluoride  used 
as  a  bath  material  in  the  electrolytic  production  of  aluminum  from  bauxite. 

In  addition  to  its  three  major  fields  of  application,  fluorspar  is  employed 
in  a  great  number  of  subordinate  capacities,  some  of  which  may  be  open  to 
considerable  development.  It  thus  finds  use  as  a  flux  in  some  blast  furnace 
operations,  and  in  iron  and  brass  furnaces;  in  the  smelting  of  gold,  silver, 
and  copper  ores;  in  the  refining  of  copper,  antimony,  and  lead;  as  a  bond  for 
the  constituents  of  emery  wheels ;  in  carbon  electrodes ;  in  the  manufacture  of 
sodium  fluoride  used  as  a  wood  preservative;  and  in  connection  with  the 
extraction  of  potash  from  feldspar  and  from  the  flue-dust  of  Portland  cement 
works.3 

Transparent,  flawless,  and  colorless,  or  nearly  colorless  pieces  of  fluorite 
are  very  valuable  as  material  for  making  apochromatic  and  semi-apochromatic 
lenses  for  use  in  the  lens  system  of  microscopes.  Such  optical  fluorite  is  very 
rare,  but  occurs  here  and  there  in  Hardin  County  in  association  with  the 
common  fluorspar,  especially  as  crystals  in  cavities  in  the  bedding  deposits. 
Pieces  suitable  for  optical  purposes  need  not  be  large,  but  must  be  flawless 
and  of  such  size  as  to  yield  lenses  %"  in  diameter.  Optical  fluorite  has  here- 
tofore been  imported  into  the  United  States,  but  Hardin  County  can  probably 
supply  the  entire  domestic  demand  for  this  specialized  material.4 

1  The  data  for  this  paragraph  were  largely  supplied  by  J.   S.   Unger,   Carnegie  Steel 
Company. 

2  From  information  communicated  by  J.  E.  Foster,  General  Chemical  Co. 
3Burchard,  E.  F.,  Our  mineral  supplies — Fluorspar:     U.  S.  Geol.   Surv.  Bull.   666-CC, 

1917.  Flourspar  and  cryolite  is  1916:  U.  S.  Geol.  Surv.,  Mineral  resources  of  the  United 
States  for  1916,  pp.  309-325.     Includes  bibliography  of  the  uses  of  flourite. 

4Pogue,  J.  E.,  Optical  fluorite  in  southern  Illinois:     111.   State  Geol.   Survey  Bull.   38, 
1918. 


ECONOMIC    GEOLOGY 


289 


Commercial  fluorspar  is  sold  in  several  grades  according  to  the  purity. 
The  highest  grade  is  known  as  "No.  1/'  or  "American  lump  No.  I99  some- 
times called  "acid  spar."  This  grade  contains  under  1  per  cent  of  silica  and 
usually  not  over  2  per  cent  of  all  other  impurities.  The  fluorspar  is  sold  in 
iump  form,  or  is  ground,  according  to  the  desire  of  the  purchaser.  "No.  1" 
spar  is  generally  white  or  clear  tinted,  and  sold  for  use  in  making  enamels, 
glasses,  and  hydrofluoric  acid,  where  material  of  a  high  degree  of  purity  is 
necessary.  The  next  grade,  "No.  2  lump/7  or  "American  lump  No.  2,"  is 
used  in  smelting  operations.  Such  spar  may  contain  up  to  4  per  cent  of 
silica  as  well  as  an  appreciable  quantity  of  calcite,  but  should  be  free  of 
metallic  minerals.  Generally  this  quality  comprises  the  more  deeply  colored 
spar  that  does  not  contain  any  metallic  sulphides.  The  lowest  grade  of 
fluorspar,  called  "gravel  spar,"  contains  sometimes  more  than  4  per  cent 
of  silica,  and  large  but  varying  amounts  of  calcite.  This  quality  comprises 
80  to  85  per  cent  of  the  domestic  fluorspar  production,  and  is  used  chiefly  as 
a  flux  in  basic  metallurgical  operations,  particularly  the  open-hearth  steel 
process.  Fluorspar  for  this  purpose  must  be  free  of  sulphide  minerals,  since 
sulphur  and  metals   (other  than  iron)   are  detrimental  to  the  finished  steel. 

PRODUCTION 

Hardin  County  contains  the  most  productive  mines  in  the  Illinois- 
Kentucky  fluorspar  district  and  is  responsible  for  more  than  two-thirds  of 
the  fluorspar  production  in  the  United  States.  The  position  held  by  the 
county  in  respect  to  the  fluorite  consumption  of  the  country  is  shown  in 
figure  25.  This  diagram  also  brings  out  the  marked  increase  in  production 
under  the  stimulus  of  the  war  demand  for  steel,  and  the  falling  off  of  imports 
from  England  in  recent  years. 

The  total  fluorspar  production  of  the  United  States  and  the  average 
price,  for  the  five  years  ending  1917,  are  shown  in  the  accompanying  table: 

Table  //. — Production  of  domestic  fluorspar,  1913  to  1917  (a) 


1913 

1914 

1915 

Aver- 

Aver- 

Aver- 

age 

age 

age 

Quantity. 

price 

Quantity. 

price 

Quantity. 

price 

per 

per 

per 

ton. 

ton. 

ton. 

Quantity. 


Aver- 
age 

price 
per 
ton. 


1917 


Quantity. 


Aver- 
age 
price 
per 
ton. 


Ground 


Lump.. 
Gravel. 


Total. 


Short  tons . 
8,137 


65. 676 


6101.767 


115.580 


$12.31 

$6.88 


$5.87 


Short  tons , 


68.842 
679. 276 


95,116 


$11.78 


$8.45 
$5.21 


Short  tons. 
10.757 


612.033 


6114.151 


136,941 


$10.80 


$7.51 


$4.89 


Short  tons. 
7.595 


$12.38 


Short  tons . 
10. 136 


614,489 


$7.94 


25.548 


6133,651 


$5.34 


6183.144 


155.735 


218.828 


$17.59 


$13.68 


$9.61 


a  Condensed  from  table   given  by   Burchard,   E.    F.,   Fluorspar  and   cryolite   in   1917 : 
U.  S.  Geol.  Surv.,  Mineral  resources  of  the  United  States  for  1917,  pt.  2,  p.  296. 
b  Some  lump  spar  is  included  with  gravel. 

—19  G 


290  GEOLOGY    OF    HARDIN    COUNTY 

In  1913,  the  total  Illinois-Kentucky  output  was  91.2  per  cent  of  the 
total  United  States  output;  in  1914  it  was  99.6  per  cent;  in  1915,  99  per  cent; 
in  1916,  93.8  per  cent;  and  m  1917,  91  per  cent.  In  1913,  Hardin  County 
produced  about  81  per  cent  of  the  total  Illinois-Kentucky  output;  in  1914 
about  79  per  cent;  from  1914  to  1916  inclusive,  the  statistics  published  by 
the  U.  S.  Geological  Survey  have  not  differentiated  the  Illinois  production 
from  that  of  Kentucky,  in  order  to  avoid  revealing  the  statistics  of  individual 
producers. 

The  diversity  of  uses  to  which  fluorspar  is  applied,  coupled  with  the 
magnitude  of  the  basic  open-hearth  steel  production  and  the  growing  im- 
portance of  hydrofluoric  acid  as  a  chemical  agent,  point  to  a  demand  for 
fluorspar  which  will  continue  to  increase  though  most  likely  not  at  the  rate 
inspired  by  war  demands.  Statistics  will,  indeed,  very  likely  show  a  marked 
temporary  slump  for  the  period  immediately  following  the  termination  of 
the  war.  Between  1910  and  1914,  the  domestic  source  met  with  considerable 
foreign  competition,  chiefly  from  the  English  deposits  in  Derbyshire  and 
Durham,  which  had  been  able,  owing  to  cheap  production,  favorable  ocean 
freight  rates,  and  bunker  shipping  capacities,  to  place  their  product  in  the 
eastern  centers  of  steel  manufacture  at  a  lesser  cost  than  the  domestic 
deposits  could  meet.  Since  1914,  however,  as  a  result  of  the  war,  the  English 
shipments  have  fallen  to  a  very  small  fraction  of  our  needs  (about  9  per  cent 
in  1916),  and  although  the  English  deposits  are  reported  to  be  far  from 
exhaustion,  it  is  questionable  if  they  will  again  assume  the  ascendancy  in  the 
eastern  markets,  since  the  American  product  is  of  higher  grade  and  the 
English  mining  costs  are  bound  to  increase.1 

It  is  believed  therefore  that  fluorspar  mining  in  Hardin  County  has  a 
good  future.  Although  it  is  not  likely  that  veins  comparable  in  size  to  the 
Good  Hope-Eosiclare  and  the  Blue  Diggings  will  be  opened  up,  vet  with  the 
establishment  of  the  railroad  through  the  county,  a  considerable  production 
from  smaller,  scattered  deposits  lies  in  prospect,  especially  after  a  period  of 
years  when  the  demand  cannot  wholly  be  filled  by  the  large  veins  now  mainly 
producing. 

SUGGESTIONS  EOR  PROSPECTING 

Fluorspar  is  so  widely  distributed  throughout  Hardin  County  that  its 
mere  presence  at  any  point  is  not  sufficient  warrant  for  prospecting.  More- 
over, probably  most  of  the  more  promising  deposits  have  already  been  located 
during  the  years  of  prospecting  that  the  district  has  enjoyed,  so  that  a  new 
deposit  must  present  many  favorable  features  in  the  face  of  a  great  number 
of  reasonably  good  known  deposits  which  are  unable  to  produce  in  competi- 
tion with  the  larger  mines.    Hence  the  use  of  the  geological  map  accompany- 

1  See  Caruthers  and  others,  Fluorspar :  special  reports  on  the  mineral  resources  of 
Great  Britain,   Geol.   Surv.   Mem..  Vol.   4,   1916. 

In  Derbyshire  the  fluorspar  has  been  obtained  at  small  cost  from  the  dump  heaps  of 
lead  and  zinc  mines,  but  this  source  is  approaching  exhaustion. 


ECONOMIC    GEOLOGY 


291 


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292  GEOLOGY    OF    HARDIN    COUNTY 

ing  this  bulletin  and  the  employment  of  a  few  simple  geological  principles 
will  save  much  time  and  expense,  whether  a  new  deposit  is  sought  or  an 
abandoned  prospect  is  being  opened  up. 

The  presence  of  fluorspar  either  with  or  without  galena  and  sphalerite, 
is  the  first-sought  clue  to  a  valuable  deposit.  Its  presence  once  determined,  it 
is  desirable  to  ascertain  if  the  deposit  lies  within  a  fault  fissure,  since  most 
of  the  producing  deposits  show  this  relation.  The  faults  of  the  region  have 
been  mapped  with  great  care  and  in  great  detail,  and  reference  to  the  geologic 
map  will  show  whether  a  deposit  in  question  has  a  favorable  position  in 
respect  to  the  known  faults.  If  it  lies  upon  a  fault  which  has  been  mapped, 
preliminary  pitting  and  trenching  may  be  undertaken  with  greater  assurance 
of  success  than  if  its  position  is  not  intersected  by  a  fault.  But  the  absence 
of  a  mapped  fault  should  not  be  accepted  as  final  disproof  of  commercial 
value,  provided  other  features  are  promising,  since  the  faulting  in  the  dis- 
trict is  very  intricate,  and  some  faults,  obscured  by  the  soil  mantle,  cannot  be 
detected  except  by  excavation;  also  small  deposits  may  occur  in  joint  planes 
that  connect  with  faults  some  little  distance  away.  On  the  whole,  however, 
the  faulting  shown  on  the  geological  map  may  be  followed  with  considerable 
confidence  as  a  guide  in  prospecting.  On  the  other  hand,  it  is  to  be  remem- 
bered that  the  presence  of  a  fault,  even  if  it  is  mineralized  with  calcite,  is 
alone  not  sufficient  evidence  of  promise,  for  many  faults  are  utterly  barren  of 
valuable  material. 

The  location  of  a  fault  may  be  recognized  in  the  field  where  two  unlike 
rock  formations,  such  as  sandstone  and  limestone,  lie  in  juxtaposition;  the 
determination  of  a  line  separating  the  distribution  of  the  two  types  will 
indicate  the  surface  trace  of  the  fault  plane;  in  many  instances  this  is  also 
expressed  topographically  by  a  ridge  of  sandstone  hardened  into  quartzite  by 
the  mineralizing  waters  which  circulated  through  the  fault  fissure.  Where 
the  opposing  sides  of  the  fault  are  limestone,  the  fault  cannot  readily  be 
determined  in  the  field  and  recourse  must  be  had  to  the  geologic  map  or 
technical  advice  must  be  sought. 

In  addition  to  the  presence  of  fluorspar  in  association  with  faulting, 
other  conditions  should  be  borne  in  mind.  The  presence  of  calcite  is  favor- 
able, especially  if  the  vein  walls  are  both  limestone,  or  if  one  is  limestone  and 
the  other  is  sandstone.  A  vein  having  both  walls  of  sandstone  gives  less 
promise,  although  it  should  be  remembered  that  the  character  of  the  walls 
changes  with  depth.  The  possibility  of  development  of  galena  or  sphalerite 
unaccompanied  by  fluorspar  should  be  viewed  with  considerable  question. 
While  these  two  minerals  are  present  in  the  large  fluorspar  veins,  and  are 
produced  as  by-products  in  the  fluorspar  mining,  there  is  slight  hope  that 
they  are  sufficiently  concentrated  at  any  place  in  the  county  to  warrant  their 
exploitation  alone.     Nor  can  the  presence  of  these  minerals  be  considered  as 


ECONOMIC    GEOLOGY  293 

an  indication  of  a  fluorspar  deposit,  since  they  are  known  to  occur  here  with- 
out fluorspar  in  several  cases. 

When  a  superficial  deposit  of  fluorspar  is  located,  there  should  be  no 
attempt  at  sinking  a  shaft  until  the  size  and  form  of  the  deposit  has  been 
carefully  determined  by  surface  pitting  and  trenching.  Too  much  emphasis 
cannot  be  placed  upon  the  necessity  for  careful  preliminary  work,  for  an 
appreciable  body  of  disseminated  fluorspar  in  the  clay  may  prove  in  depths 
of  thirty  to  forty  feet  to  be  the  disintegrated  top  of  a  vein  too  narrow  for 
successful  working.  After  the  general  trend  of  the  fluorspar  body  has  been 
determined  by  close  pitting,  a  trench  should  be  dug  at  right  angles  to  the 
course  at  what  appears  to  be  its  widest  portion.  The  trench  should  be 
carried  deep  enough  to  show  up  the  structural  character  and  width  of  the 
vein,  after  which  its  length  should  be  explored  by  means  of  similar  trenches 
at  intervals  of  a  hundred  feet  or  so  along  its  trend. 

THE  PRINCIPAL  MINES    OF   HARDIN   COUNTY 

While  there  are  a  great  many  mines  and  prospects  throughout  Hardin 
County,  only  a.  few  are  actually  producing  important  quantities  of  fluorspar. 
Some  are  being  operated  by  individuals  as  lessees  and  are  subject  to  fitful 
operations  as  market  conditions  change.  Since  the  beginning  of  the  war,  and 
particularly  since  1916,  the  rapid  rise  in  the  price  of  fluorspar  has  stimulated 
production,  with  the  result  that  some  of  the  abandoned  properties  have  been 
reopened  and  prospecting  for  new  locations  undertaken.  This  chapter  cannot 
treat  separately  all  the  new  prospects,  a  few  of  which  may  prove  to  be  valuable 
deposits,  and  the  majority  of  which  will  either  prove  to  be  valualess,  or 
perhaps  workable  only,  under  the  stimulus  of  highly  favorable  market  con- 
ditions, or  a  change  in  present  transportation  facilities. 

A  few  mines  were  opened  solely  as  lead  or  zinc  producers,  and  contain  no 
fluorspar.  All  such  mines  have  been  abandoned,  as  in  no  case  has  a  deposit 
of  lead  or  zinc  minerals  been  found  of  sufficient  size  to  warrant  continuance 
of  operations  for  the  recovery  of  those  minerals  alone. 

Rosiclare  mine. — This  mine,  owned  by  the  Eosiclare  Lead  and  Fluorspar 
Company,  is  on  the  Good  Hope-Bosiclare  vein  and  has  been  mentioned  in 
the  discussion  of  that  vein  earlier  in  the  chapter.  It  is  located  in  the  north- 
western side  of  the  settlement  of  Eosiclare,  and  is  one  of  the  most  important 
mines  of  the  fluorspar  district.  Its  history  has  been  one  of  almost  continuous 
operation  since  the  earliest  days  of  mining  in  the  region.  Originally  it 
formed  a  part  of  the  Pell  property  on  which  fluorspar  was  discovered  in 
1842-43,  and  not  long  after  mined.  It  has  been,  therefore,  very  extensively 
developed.  The  main  shaft  is  now  620  feet  deep.  An  older  shaft,  a  few 
hundred  feet  southwest  of  the  first,  reaches  to  the  420-foot  level.  Levels  are 
open  at  depths  of  235,  320,  420,  and  520  feet,  but  all  present  operation? 


294 


GEOLOGY  OF  HARDIN  COUNTY 


100- 


200 


300- 


400 


St.  Louis 


h  ig.  26.— Idealized  geologic  section  through  the  air  shaft  of  the  Rosiclare  mine. 


ECONOMIC    GEOLOGY  295 

are  carried  on  below  235  feet,  and  mostly  below  320  feet.  Old  workings 
between  the  235-foot  level  and  the  surface  are  no  longer  accessible. 

The  vein  is  nearly  vertical  and  its  average  strike  is  abont  N.  20°  E.  In 
places  its  strike  is  as  much  as  N.  35°  E.  In  width  it  varies  considerably, 
reaching  a  maximum  of  about  30  feet,  though  it  is  more  commonly  between 
6  and  12  feet.  Eigure  26  shows  the  vein  relationships  and  stratigraphy  at 
the  mine. 

Mining  is  generally  carried  on  in  shrinkage  stopes,  though  some  under- 
hand stopes  have  been  developed  in  the  past. 

Daisy  mine. — This  mine  is  owned  and  operated  by  the  Eosiclare  Lead 
and  Fluorspar  Company,  and  is  supposed  to  be  on  the  Blue  Diggings  vein. 
This  may  prove  to  be  true,  but  until  the  drifts  are  carried  farther  south  the 
identity  cannot  be  verified.  The  average  course  of  the  Blue  Diggings  vein 
is  about  N.  30°  E.,  but  in  the  Blue  Diggings  mine  of  the  Fairview  Company, 
strikes  of  N.  23°  E.  and  N.  40°  E.  were  observed.  The  vein,  however,  is 
irregular  and  the  fluorspar  bodies  appear  to  be  occupying  a  broad  zone  of 
fracture  rather  than  a  definite  fault  fissure.  In  the  Daisy  mine,  toward  the 
south  end  of  the  200-foot  level,  the  average  course  of  the  vein  changes  from 
about  N.  40°  E.  to  a  few  degrees  west  of  north.  At  this  bend  no  indications 
of  a  cross  fault  are  apparent,  the  change  in  direction  appearing  to  be  primary. 
Xorth  of  this  bend  the  dip  of  the  vein  is  toward  the  northwest,  and  south  of 
the  bend,  toward  the  southwest,  in  each  case  about  70°.  In  the  Blue  Diggings 
mine  of  the  Fairview  Company,  although  the  dip  is  variable  with  depth,  in 
general  it  is  toward  the  southeast.  Such  lack  of  correlation  of  strikes  and 
dips  in  the  two  mines  suggests  a  respective  location  on  different,  probably 
intersecting  veins.  At  the  surface,  geologic  conditions  are  obscure  because  of 
the  lack  of  rock  outcrops,  and  no  second  fault  in  the  vicinity  of  the  Daisy 
mine  is  determinable.  According  to  Weller1  the  fault  on  which  the  Blue 
Diggings  mine  is  located  runs  through  or  close  to  the  Daisy.  In  view  of  this 
and  of  the  ill-defined  character  of  the  mineral  body  at  the  Blue  Diggings, 
the  faulting  may  be  expressed  by  the  broad  zone  of  fracture,  as  suggested 
above,  in  which  the  mineral  bodies  could  wind  in  serpentine  courses,  while 
the  general  strike  of  the  fault  zone  can  be  said  to  be  about  N.  30°  E. 

The  fluorspar  in  the  Daisy  mine  is  particularly  pure  and  white,  with 
the  bluish  tinge  that  characterizes  the  "Blue  Diggings"  mineral.  The  mineral 
body  in  the  Daisy  is  12  feet  wide  in  places,  but  pinches  to  2  feet  at  the  south 
face. 

Fairview  mines. — The  shaft  of  the  Good  Hope  mine  is  located  at  Fairview 
about  three-fourths  of  a  mile  west  of  Eosiclare  and  one-half  mile  back  from 
Ohio  River.  The  mine  is  owned  and  operated  by  the  Fairview  Fluorspar  and 
Lead  Company,  and  is  believed  to  be  on  the  same  vein  as  the  Eosiclare  mine. 
The  shaft  was  started  about  1862,  althongh  the  existence  of  ore  was  discovered 

1  Personal  communication. 


296 


GEOLOGY   OF   HARDIN    COUNTY 


in  1842.  The  mine  was  worked  in  a  small  way  until  1874  without  much 
interruption,  but  thereafter  was  shut  down  for  a  few  years.  The  operators 
of  the  Rosiclare  mine  worked  it  under  a  lease  between  1890  and  1895.    From 


Paint  Creek 


.nt)*- 


Bethel 


Renault  and   Shetlerville 


'Lower   Ohara" 


Rosiclare  •'.*." 


Fredonia 


St.  Louis 


Renault  and   Shetlerville 

"Lower  Ohara" 

- 

'.'..'. 'Rosic]are\  '.'.'.'.'.' 

Fredonia 

and 
St.  Louis 

I      ! 

0  1 


100- 


200 


300 


400 


600 


Fig.  27. — Idealized  geologic  section  through  the  new  Good  Hope  shaft. 


1905  to  1913  the  present  company  operated  the  mine  through  the  original 
Good  Hope  shaft,  but  in  1913  this  shaft  gave  trouble  and  was  abandoned.  In 
August,  1917,  work  on  reopening  the  shaft  was  commenced.     The  Good  Hope 


ECONOMIC   GEOLOGY 


297 


shaft  was  originally  sunk  on  the  vein  to  a  depth  of  503  feet  and  in  1913  it 
had  a  drift  development  on  6  levels  totalling  5,500  feet.  The  fluorspar  taken 
from  the  mine  was  of  high  grade.  The  ore  bodies  were  short  but  of  goo'd 
width,  as  wide  as  25  feet  in  places.  Figure  27  shows  the  vein  relationships 
and  stratigraphy  at  the  Good  Hope  mine. 


Unconsolidated 


surface       materials 


Fig.  28. — Idealized  geologic  section  through  the  Annex  shaft. 


The  Fairview  Company  in  1909  opened  up  an  old  shaft  on  the  same  vein 
about  1,700  feet  north  of  the  Good  Hope  shaft,  and  extended  it  to  300  feet. 
Operations  ceased  in  1914,  however,  most  of  the  fluorspar  having  been 
removed. 

In  1911  work  was  begun  on  the  Annex  and  Extension  mines,  1,700  feet 
south  of  the  Good  Hope  shaft.     As  stated  earlier,  this  may  be  on  the  same 


298  GEOLOGY    OF    HARDIN    COUNTY 

vein  as  the  Good  Hope,  or  it  may  be  on  a  branch  of  the  main  Good  Hope- 
Bosiclare  vein.  The  Annex  shaft  (fig.  28)  is  now  340  feet  deep  and  the 
Extension  440  feet.     The  mine  is  in  operation. 

Blue  Diggings  mine. — The  Fairview  Fluorspar  and  Lead  Company  be- 
gan operations  on  this  mine  in  1910.  It  is. situated  on  the  Blue  Diggings 
vein  heretofore  described.  The  shaft  is  located  about  a  quarter  of  a  mile 
west  of  the  main  shaft  of  the  Eosiclare  mine,  in  the  NE.  y±  SW.  14  sec.  32. 
An  attempt  to  operate  an  old  shaft  was  soon  abandoned  and  a  new  one 
started.  The  shaft,  which  is  now  540  feet  deep,  was  driven  in  the  hanging 
(east)  wall  and  passed  through  the  vein  at  the  200  foot  level.  At  the  500 
foot  level  the  vein  is  150  feet  east  of  the  shaft.  The  general  characteristics  of 
the  vein  are  described  earlier  in  the  chapter,  its  dip  direction  being  radically 
different  from  that  of  the  Good  Hope-Eosiclare  vein,  as  shown  in  figure  29. 

Hillside  mine. — This  mine,  opened  in  the  early  part  of  1919  by  the 
Inland  Steel  Company,  is  situated  in  the  NE.  %  of  sec.  32,  T.  12  S.,  E.  8  E., 
three-quarters  of  a  mile  north  of  Eosiclare.  At  the  time  of  the  writer's  visit 
a  shaft  had  been  sunk  to  a  depth  of  170  feet  and  a  cross-cut  made  to  the  vein 
at  this  point.  The  location  of  the  workings  and  the  character  of  the  vein 
and  wall  rocks  point  to  the  probability  that  the  mine  is  located  on  the  Good 
Hope-Eosiclare  vein. 

Clement  mine. — This  mine  is  located  about  two  miles  north  of  Eosi- 
clare, in  the  SW.  %  SW.  14  sec.  21.  As  the  mine  is  no  longer  in  operation 
and  apparently  has  not  been  for  several  }^ears,  the  underground  workings  were 
not  accessible.  The  dump  shows  limestone  country  rock  with  coarse  calcite, 
and  fluorspar  replacing  the  calcite,  as  at  the  mines  around  Eosiclare.  Accord- 
ing to  Bain1,  who  examined  the  workings  in  1903,  the  vein  is  situated  in  a 
fault  of  slight  displacement.  Weller2  considers  this  fault  the  continuance  of 
the  combined  Eosiclare  and  Blue  Diggings  faults,  which  come  together  prob- 
ably not  more  than  half  a  mile  south  of  the  Clement  shaft. 

Twitchel  mine. — This  is  a  small  mine  located  in  the  NE.  14  NE.  14  sec. 
24,  T.  12  S.,  E.  7  E.,  just  north  of  St.  Josephs  school.  It  has  a  shaft  55  feet 
deep  and  a  drift  30  feet  long.  The  vein  runs  N.  5°  W.,  dips  70°  E.,  and  is 
about  three  feet  wide.  Calcite  and  fluorspar  are  the  vein  minerals,  and  both 
walls  are  limestone.     It  does  not  appear  to  be  in  a  fault. 

Preen  mine. — This  mine,  located  in  the  NW.  %  NW.  %  sec-  19>  T-  12 
S.,  E.  8  E.,  was  operated  by  lessees  in  1917,  and  a  small  quantify  of  fluorspar 
was  produced.  An  old  shaft  extends  to  a  depth  of  75  feet.  A  new  shaft  was 
sunk  to  30  feet.  Near  the  surface  the  fluorspar  is  somewhat  "pockety"  in 
clay,  and  resembles  superficial  deposits.  At  a  depth  of  75  feet  limestone  walls 
were  found.     Calcite  appears  as  a  vein  mineral. 

1  Op.  cit.,  p.   47. 

2  Personal   communication. 


ECONOMIC    GEOLOGY 


299 


Map  Soale  In  Feet 
inyo  3000 


Fredonla 


Renault 

and 

Shetlervllle 


"Lower  Ohara' 


■'■:■  Ro'siqlare ; .  • 

Fredonla 

and 
St.  Louis 


Oi 


100- 


200 


300 


400 


500 


Fig.  29. — Map  and  idealized  geologic  section  to  show  the  vein  relationships 
and  stratigraphy  at  the  Blue  Diggings  shaft.  The  zone  of  extensive  fracturing  is 
only  very  diagrammatically  shown. 


300  GEOLOGY    OF    HARDIN    COUNTY 


en  I 


Pell  mine. — The  Pell  mine  is  located  about  one  mile  west  of  the  Pre 
mine,  in  NE.  %  NW.  %  sec.  24.  The  mine  was  abandoned  for  several  years 
until  the  spring  of  1919,  when  a  lessee  started  to  sink  a  new  shaft.  The  old 
shaft  was  95  feet  deep  and  the  dump  pile  showed  that  vein  materials  are 
coarse  calcite,  fluorspar,  galena,  and  blende.  Pits  along  the  outcrop  of  the 
vein  show  that  it  is  located  in  a  fault  with  limestone  and  sandstone  as  the 
wall  rocks.  The  fluorspar  seen  in  the  dump,  and  that  removed  from  a  very 
shallow  depth  by  the  present  lessee  appeared  to  be  of  good  grade. 

Stewart  mine. — This  mine  is  located  about  one  mile  northwest  of  the 
Pell  mine  near  the  center  of  sec.  14,  T.  12  S.,  R.  71  E.  It  was  being  operated 
at  the  time  of  the  writer's  first  visit  to  the  fluorspar  region  in  1917  by  open 
pit  operations  but  a  shaft  had  been  sunk  to  a  depth  of  75  feet  in  the  hanging 
(east)  wall.  The  vein  runs  N.  25°  E.  and  dips  about  80°  E.  In  an  apen 
pit  200  feet  north  of  the  shaft  a  vein  of  fluorspar  2%  to  4  feet  wide  was  seen. 
The  open-cut  extended  for  about  a  hundred  feet  along  the  vein.  No  calcite 
appeared  in  the  open  pit.  At  a  depth  of  25  feet  the  walls  were  reached,  lime- 
stone on  the  west  and  sandstone  on  the  east,  showing  the  existence  of  a  fault. 
Some  galena  is  present  in  the  deposit.  An  old  dump  pile  nearby,  said  to  have 
come  from  an  old  shaft  driven  to  a  depth  of  100  feet,  showed  much  coarse 
calcite  in  the  wall  rock. 

Martin  mine. — At  the  Martin  mine,  NW.  %  NE.  %  sec.  17,  about  four 
miles  directly  north  of  Rosiclare,  the  dump  pile  shows  blue  fluorspar  in 
limestone,  with  a  small  amount  of  calcite.  The  vein  is  situated  in  a  fault 
with  walls  of  limestone  and  quartzitic  sandstone.  No  lead  or  zinc  minerals 
were  seen.  The  underground  workings  were  abandoned  and  inaccessible.  The 
property  is  controlled  by  the  Rosiclare  Lead  and  Fluorspar  Company. 

Miller  mine,  M etcher  Hills. — This  mine  is  located  about  l1/^  miles  north- 
east of  Shetlerville,  and  just  east  of  Melcher  Hills,  in  the  SW.  *4  SW.  % 
sec.  25.  The  mine  is  entered  by  tunnels  in  the  hillside  from  which  an  irregu- 
lar system  of  rooms  has  been  developed.  The  deposit  appears  to  be  of  the 
bedding  type  for  the  most  part  but  several  irregularly  trending  narrow  veins 
are  to  be  seen.  Besides  fluorspar,  galena  is  prominent.  A  shaft  was  being 
sunk  in  August,  1917,  and  was  75  feet  deep  at  that  time,  but  was  inaccessible 
to  the  writer.  It  was  stated  that  a  vein  was  struck  running  in  a  northeasterly 
direction.     Limestone  wall  rocks  were  found  at  this  depth. 

Lead  Hill  mines. — Lead  Hill  is  situated  in  the  western  half  of  sec.  4, 
T.  12  S.,  R.  9  E.,  about  four  miles  northwest  of  Cave  in  Rock  In  the  south- 
western side  of  this  hill  are  several  small  mines  that  represent  sporadic 
operations  extending  over  many  years.  At  the  time  of  the  writer's  visit  some 
of  the  workings  were  being  reopened.  The  deposits  of  this  locality  have  been 
described  in  the  section  on  "bedding  deposits." 

The  workings  of  the  Lead  Hill  Lead  and  Spar  Company  consists  of  a 
series  of  chambers  entered  bv  tunnels  in  the  hillside.    Since  these  deposits  are 


ECONOMIC    GEOLOGY  301 

practically  horizontal  and  never  more  than  two  or  three  feet  in  thickness, 
there  is  only  one  level  of  underground  workings.  An  old  and  now  abandoned 
mill,  containing  crushers,  trommels,  and  jigs,  and  a  good  sized  dump  pile, 
testifies  to  earlier  attempts  at  large  scale  operations. 

The  deposits  are  banded  and  are  replacements  of  the  nearly  horizontal 
limestone.  At  Lead  Hill  the  mineralized  beds  may  continue  with  more  or 
less  thinning  and  interruption  entirely  through  the  hill  to  the  east  slope,  for 
outcrops  of  the  banded  fluorite  are  found  in  several  places  on  that  side  at 
nearly  the  same  elevation  as  that  at  which  the  deposits  occur  on  the  west 
side.  Some  outcrops  on  the  east  side  of  Lead  Hill  which  occur  at  a  somewhat 
lower  level  than  those  mentioned  above  have  recently  been  slightly  worked. 
Part  of  the  material  here  has  prominent  bands  of  quartz  crystals  alternating 
with  fluorspar.  The  general  structural  relationships  appear  to  be  otherwise 
identical  in  character  with  the  other  bedding  deposits. 

Although  a  little  sphalerite  is  to  be  found  at  Lead  Hill,  it  is  not  nearly 
so  abundant  as  galena.  Galena  appears  in  pockets  and  as  well-formed  cubes 
along  the  sides  of  some  of  the  replacement  bands.  Cerussite  is  common  as  a 
coating  of  the  galena  and  of  some  of  the  fluorite  grains  of  the  finer  bands. 
The  drusy  yellow  variety  of  smithsonite  (zinc  carbonate),  called  "turkey 
fat,"  may  occasionally  be  found. 

Some  fluorspar  was  found  here  of  such  character  as  to  warrant  careful 
search  for  spar  of  optical  quality.  Quite  flawless  and  nearly  colorless  pieces 
are  fairly  abundant,  and  while  no  very  large  pieces  were  found  it  is  alto- 
gether probable  that  here  is  a  locality  from  which  mineral  suitable  for  lenses 
could  be  obtained. 

Owing  to  the  banded  character  of  the  fluorspar  deposit  and  the  relatively 
poor  quality  of  many  of  the  bands,  the  product  of  these  mines  could  probably 
not  compete  with  the  higher  grades  of  vein  fluorspar.  In  some  instances 
however  very  good  material  is  obtained. 

Cave  in  Rock  mine. — In  the  N"W.  14  NE.  %  sec-  4,  about  three-quarters 
of  a  mile  northeast  of  the  Lead  Hill  mine,  another  bedding  deposit  of  fluor- 
spar is  being  worked.  A  very  irregular  bed  of  the  mineral,  in  places  three 
feet  thick,  underlies  a  capping  of  dense  limestone.  The  deposit  is  banded 
similar  to  the  Lead  Hill  occurrences. 

This  mine  is  of  the  open-pit  type,  although  a  shaft  is  present  and  some 
drifting  has  been  done. 

Some  exceptionally  fine  specimens  of  optical  quality  have  been  obtained 
from  pockets  in  this  mine,  and  the  deposit  holds  considerable  promise  as  a 
source  of  optical  fluorite.1 

Empire  mine. — The  Empire  mine  is  situated  in  Pope  County,  in  the 
SW.  14  SE.  %  sec.  27,  T.  11  S.,  E.  7  E.,  less  than  half  a  mile  west  of  the 
Hardin  County  line.     The  original  mine  is  now  abandoned.     A  shaft  and 

Bull*  ?8giq'l8J*    E*'    °ptical    fluorite    in    southern    Illinois:      111.    State    Geological    Survey 


302  GEOLOGY    OF    HARDIN    COUNTY 


th 


open-cut  were  seen,  and  a  dump  pile  in  which  were  found  specimens  of  bo 
limestone  and  sandstone,  containing  fluorspar,  blende,  and  coarse  calcite. 
The  relations  are  similar  to  those  in  the  mines  at  Eosiclare.  Underground 
workings  were  not  accessible  but  Bain1  describes  the  vein  as  "6  to  10  feet 
wide  and  with  well-developed  walls.  The  vein  matter  consists  of  brecciated 
limestone  cemented  by  fluorspar  and  calcite  intimately  intergrown.  In  this 
matrix  galena,  blende,  pyrite,  and  chalcopyrite  occur."  Zinc  carbonate  is 
prominent  on  some  of  the  pieces  in  the  dump  taken,  presumably,  in  the  open 
cut  near  or  at  the  surface. 

Pierce  mines. — The  Pierce  mines  are  situated  about  half  a  mile  south 
of  the  old  Empire  shaft.  There  are  several  open-cuts  on  the  property,  the 
general  distribution  of  which,  together  with  the  character  of  the  fluorspar 
bodies,  indicates  the  presence  of  at  least  two  veins — one  running  about  N. 
75°  E,  and  the  other  about  N.  45°  E.  Figure  21  is  a  sketch  map  of  the 
pitted  ground. 

The  fluorspar  in  the  open-cuts  is  colored,  transparent  to  translucent,  and 
pure.  It  is  somewhat  dispersed  through  red  and  yellow  clays,  but  sufficiently 
well  localized  to  indicate  the  probable  existence  of  very  well  defined  veins 
at  not  much  greater  depths.  Some  rounded  boulders  of  limestone,  remnants 
of  the  walls,  are  encountered  during  the  mining  operations.  These  boulders 
are  traversed  by  narrow  seams  of  calcite  and  fluorspar.  Some  coarse  calcite 
is  found  on  them.  At  one  point  rounded  calcite  fragments  were  found  in  the 
main  mineral  body. 

One  of  the  pits  shown  in  figure  21  was  dug  to  a  depth  of  forty  feet  where 
limestone  was  encountered.     This  pit  is  not  being  worked. 

South  and  west  of  these  pits  are  several  abandoned  shafts  and  prospect 
holes.  One  of  these  is  the  Hubbard  shaft  originally  sunk  by  the  Grand 
Pierre  Mining  Company. 

The  fluorspar  of  this  locality  is  of  such  character  as  to  warrant  search 
for  material  of  optical  quality. 

Other  mines  near  the  Empire. — North  of  the  Empire  shaft  may  be  seen 
several  abandoned  mines,  among  them  the  Big  Joe,  Hutchinson,  Eainey, 
Baldwin,  and  Hicks,  which  are  described  by  Bain.2  All  of  them  are  now 
unimportant.  While  there  are  a  few  shafts  on  these  properties,  most  of  the 
workings  are  open-cuts  and  in  the  nature  of  prospects.  North  of  the  Empire 
mine  several  open-cuts  have  recently  been  dug  by  the  operators  of  the  Pierce 
mines. 

Hamp  mines  and  adjacent  prospects. — In  tne  NW.  V±  sec.  18,  about  four 
miles  northeast  of  the  Empire,  are  several  shafts  which  have  apparently  not 
been  operated  for  a  number  of  years.  These  shafts  comprise  the  Hamp  mines 
and  adjacent  prospects.     Dump  piles  displayed  limestone  with  a  little  fluor- 

1Op.  cit.,  p.   49. 

2  Op.   cit,  pp.   50-52. 


ECONOMIC    GEOLOGY 


303 


spar,  calcite,  galena,  and  blende.  The  course  of  the  vein  at  the  Hamp  mine 
is  said  to  be  X.  60°  E.  No  faulting  is  discernible  at  the  surface.  The  vein 
may  be  filling  a  fissure  of  very  little  or  no  displacement  connecting  at  some 
distance  with  a  more  pronounced  fault  fissure. 

At  a  small  cut  west  of  the  shafts,  banded  fluorspar  of  the  "bedding"  type 
of  deposit  was  seen.  Unlike  the  fluorspar  near  Cave  in  Rock  the  mineral  of 
these  bands  was  very  deeply  colored  and  nearly  opaque.  When  freshly  broken, 
the  mineral  from  this  deposit  gave  a  strong  odor  of  petroleum. 

Several  deposits  of  gravel  spar  have  been  dug  recently  in  the  vicinity 
north  of  the  mine. 


Fig.  30. — View  cf  a  mass  of  fluorspar  on  the  weathered  apex  of  a  vein.  Bald- 
wins Run,  Pope  County,  just  west  of  the  county  line  near  the  center  of  the  east 
side  of  sec.  27,  T.  11  S.,  R.  7  E. 


Lee  mine. — The  Lee  mine  is  situated  about  three  and  three-quarters  of 
a  mile  due  east  of  the  Hamp  mine,  in  the  NW.  %  NW.  %  sec.  14,  T.  11  S., 
R.  8  E.  A  shaft  71  feet  deep  has  been  dug,  meeting  a  vein  8  feet  in  thick- 
ness. The  vein  strikes  N.  55°  E.  and  dips  80°  SE.  It  can  be  traced  on  the 
surface  for  nearly  half  a  mile.  Faulting  is  shown  by  a  hanging  wall  of  lime- 
stone and  a  footwall  of  quartzite.  Purple  and  white  fluorspar  composes  the 
vein  matter,  neither  metallic  sulphides  nor  calcite  being  present.  The  mine 
was  being  worked  in  September,  1917. 

Rose  mine. — At  this  small  abandoned  mine,  situate:!  in  the  SE.  14  sec. 
30,  T.  11  S.,  R.  8  E.,  some  pieces  of  fuorspar  of  such  character  as  to  suggest 


304  GEOLOGY    OF    HARDIN    COUNTY 

a  likely  source  of  the  mineral  for  optical  purposes  were  obtained  from  the 
clump.  It  was  slightly  tinted,  crystalline,  showing  no  double  refraction,  and 
small  pieces  were  remarkably  free  of  flaws.  Much  of  it,  however,  contained 
enclosed  grains  of  pyrite  and  chalcopyrite. 

Miscellaneous  mines  and  prospects. — Besides  the  mines  mentioned  above, 
many  other  abandoned  mines  and  prospects  are  to  be  found  in  Hardin  County, 
among  them  several  mines  mentioned  by  Bain,  but  not  included  in  this  report 
because  of  their  unimportance  and  the  fact  that  nothing  could  be  learned 
about  the  character  of  most  of  them.  Also  hundreds  of  new  prospect  pits 
dot  the  ground  all  through  the  county,  some  of  which  will  probably  become 
important  later.  It  would  be  impracticable  to  list  and  describe  all  of  them. 
Those  that  have  been  described  comprise  the  active,  and  the  most  important 
of  the  abandoned  mines,  as  seen  at  the  time  of  this  investigation. 

Iron  Ore,  Limestone,  Eoad  Metal,  Oil,  and  Gas 

By  Chas.   Butts 

IRON   ORE 

The  existence  of  iron  ore  in  Hardin  County  has  been  known  ever  since 
its  settlement,  and  the  deposits  were  utilized  in  early  days  at  the  old  Illinois 
Furnace  on  Big  Creek,  three  and  one-half  miles  northwest  of  Elizabethtown, 
and  at  the  Martha  Furnace  in  sec.  2  of  T.  12  S.,  E.  8  E.  The  Illinois  Furnace 
obtained  its  ore  largely  from  land  immediately  to  the  east  in  the  SW.  %  sec- 
3,  and  the  N*E.  %  sec.  9,  T.  12  S.,  E.  8  E.,  on  the  McKernan  farm.  The 
Martha  Furnace  also  secured  its  ore  from  its  immediate  vicinity.  As  usual 
with  such  iron  deposits,  the  ore  is  limonite,  a  hydratecl  iron  oxide,  Fe2(OH)3. 
As  usual,  also,  it  occurs  in  the  form  of  small  pellets  or  gravel  (wash  ore), 
nuggets,  and  larger  irregular  chunks  and  masses  scattered  through  clay  and 
soil,  with  all  of  which  there  is  also  much  chert,  and  possibly  some  sandstone. 
All  of  this  material  is  residual  from  the  decay  of  rocks,  mainly  of  limestone. 
The  deepest  accumulations  of  this  kind  are  likely  to  be  located  along  the  sides 
of  the  knobs  and  spurs,  as  can  be  seen  at  the  old  diggings  on  the  McKernan 
property  which  supplied  Illinois  Furnace.  Some  of  these  old  pits  are  said 
to  have  been  90  feet  deep.  On  the  sides  of  the  pits  next  to  the  spurs  there  are 
irregular  masses  of  limestone,  exposed  in  digging  the  ore.  These  limestone 
masses  now  projecting  up  into  the  clay  and  earth  which  holds  the  ore,  are 
undisintegrated  and  undissolved  portions  of  the  once  continuous  rock  strata. 
It  is  only  where  the  residual  clay  is  deep  that  much  ore  can  accumulate,  and 
it  is  useless  to  look  for  it  elsewhere.  Other  localities  where  such  iron  ore  has 
been  dug,  or  where  more  or  less  limonite  float  occurs  in  the  gullies,  are  the 
SW.  %  NE.  %  sec.  34,  T.  11  S.,  E.8E.;  SW.  %  sec.  35,  T.  11  S.,  E.  8  E.; 
sec.  2,  T.  12  S.,  E.  8  E.;  NE.  14  sec.  24,  T.  11  S.,  E.  7  E.;  SW.  %  sec.  13, 
T.  11  S.,  E.  7  E. ;  and  on  Hicks  Branch  just  west  of  the  church  in  the  SE.  Vi 


ECONOMIC    GEOLOGY  305 

SW.  V4  sec.  26,  T.  11  S.,  R.  7  E.  At  the  last  described  place  large  masses  of 
limonite  are  exposed  over  a  few  square  rods  of  surface  on  the  steep  bank  on 
the  south  side  of  the  road.  All  the  known  occurrences  of  iron  ore-  deposits  in 
Hardin  County  are  in  areas  underlain  by  the  Fredonia  or  St.  Louis  lime- 
stones, and  in  that  particular  they  are  like  most  of  the  extensive  limonite 
deposits  in  eastern  United  States,  as  in  Pennsylvania  and  Alabama,  where 
the  ore  occurs  in  residual  material  accumulated  upon  the  outcrops  of  thick 
limestone  formations. 

It  is  safe  to  affirm  that  there  is  considerable  iron  ore  in  Hardin  County, 
but  no  definite  or  reliable  estimate  of  the  quantity  can  be  made  with  our 
present  knowledge,  as  such  estimates  can  only  be  made  after  extensive  pros- 
pecting. According  to  Owen1  the  limonite  ore  of  the  county  contains  over 
50  per  cent  metallic  iron,  which  is  about  the  usual  metallic  content  of  the 
limonite  ores  now  being  used.  The  composition  of  a  specimen  of  ore  from 
the  bank  of  the  old  Martha  Furnace  in  sec.  2,  T.  12  S.,  E.  8  E.,  is,  according 
to  Owen  as  follows : 

Composition  of  iron  ore  from  bank  of  Martha  Furnace 

Water  H=10.8 

Siliceous  earth 5.0 

Peroxide  of  iron Fe2O3=80.0=56.02  Fe 

Alumina Al  3.7 

Loss  and  alkalies  not  estimated 0.5 


100. 
Owen  advanced  the  theory  that  these  ores  are  derived  from  fissure  de- 
posits of  magnetite  extending  to  great  depths.  He  thought  that  this  deep 
seated  ore  was  taken  into  solution  by  ascending  carbonated  waters  and 
carried  to  the  surface  and  redeposited  in  the  upper  part  of  the  fissure  or  in 
the  earth  above,  as  they  now  exist.  This  theory  has  not  been  verified,  and 
no  such  occurrence  is  known  in  regions  of  exclusively  sedimentary  rocks. 
The  actual  deposits  of  ore,  on  the  other  hand,  agree  fully  in  their  character 
and  manner  of  occurrence  with  limonite  ore  deposits  in  other  parts  of  the 
country  which  are  entirely  of  superficial  origin,  and  these  Hardin  County 
deposits  are  undoubtedly  of  such  an  origin. 

LIMESTONE 

An  abundance  of  high  grade  limestone,  well  suited  for  the  manufacture 
of  lime,  cement,  and  ground  rock  for  fertilizer,  exists  in  Hardin  County. 
The  Fredonia  limestone  carries  the  best  rock  for  lime  and  cement.  The 
white  oolite  beds  of  this  formation,  utilized  for  such  purposes  elsewhere,  are 

1  Owen.  D.  D.,  Report  on  Saline,  coal  and  manufacturing  companies  properties. 
— 20  G 


306  GEOLOGY    OF    HARDIN    COUNTY 

the  most  desirable.  Such  oolite  beds  constitute  a  large  part  of  the  full  thick- 
ness of  the  Fredonia  limestone,  and  the  formation  has  large  areas  of  outcrop 
in  the  county,  with  many  favorable  situations  for  quarrying.  Probably  the 
best  site  for  exploiting  the  Fredonia  is  at  Lead  Hill,  four  miles  northwest 
of  Cave  in  Eock,  in  the  western  part  of  sec.  4,  T.  12  S.,  R.  9  E.  At  this 
locality  there  is  fully  100  feet  of  the  limestone  exposed  entirely  above  the 
surrounding  level  land,  so  that  a  quarry  would  be  naturally  drained  and  the 
rock  could  be  handled  by  gravity.  The  strata  are  nearly  flat,  and  a  very  large 
body  of  rock  is  accessible  without  stripping;  only  20  to  50  feet  of  stripping 
would  be  required  on  the  summit  of  the  hill,  and  most  of  the  material  to  be 
moved  would  be  suitable  for  road  metal.  In  addition  to  the  limestone  at  this 
locality,  a  considerable  amount  of  fluorspar  and  lead  could  be  recovered  in 
connection  with  the  quarrying.  Hardin  County  is  the  nearest  source  of 
supply  of  ground  limestone  and  crushed  rock,  for  a  large  territory  to  the 
north  in  Illinois  and  Indiana,  and  with  favorable  transportation  facilities 
Lead  Hill  seems  to  offer  an  opportunity  for  profitable  enterprise.  The  other 
limestone  formations  of  the  county  should  supply  good  rock  for  fertilizer  and 
other  purposes. 

The  only  quarry  of  importance  in  active  operation  in  the  county,  is  at 
Jacks  Point,  on  the  bank  of  Ohio  River  about  one  mile  below  Elizabethtown. 
The  rock  quarried  at  this  locality,  which  is  from  about  the  dividing  line 
between  the  St.  Louis  and  Ste.  Genevieve  limestones,  is  transported  on  barges 
clown  the  river  for  use  in  work  on  the  river  banks.  In  the  past  a  number  of 
quarries  have  been  operated  in  the  river  bluffs  above  and  below  Rosiclare  in 
the  Fredonia  limestone  of  the  Ste.  Genevieve,  but  none  of  them  is  in  use 
at  the  present  time. 

The  Menard  limestone  would  be  serviceable  for  fertilizer  and  other 
purposes  wherever  it  is  well  exposed  in  the  county,  and  the  Glen  Dean  also 
in  the  eastern  part  of  the  county.  Much  of  the  St.  Louis  limestone  would  be 
suitable  for  agricultural  lime  and  for  crushed  rock,  but  most  of  it  is  too 
siliceous  for  the  manufacture  of  lime  or  cement. 

No  chemical  analyses  have  been  made  of  the  Hardin  County  limestones, 
but  from  analyses  of  rock  from  other  regions  the  Fredonia  oolite  is  known 
to  be  of  a  high  grade,  and  as  the  formation  here  preserves  all  of  its  outward 
characteristics  shown  elsewhere  where  it  has  been  tested,  the  conclusion  is 
justified  that  it  is  of  high  grade  here  also. 

ROAD   METAL 

In  addition  to  its  many  limestone  formations  which  would  afford 
crushed  stone  for  road  metal,  the  county  has  a  very  great  reserve  of  excel- 
lent road  material  in  the  vicinity  of  Hicks  dome,  in  the  form  of  broken 
chert,  most  of  the  chert  being  derived  from  the  Osage  formation,  but  with 
a  considerable  proportion  from  the  Warsaw,   St.  Louis,  and  Ste.  Genevieve 


ECONOMIC    GEOLOGY  307 

limestones.  These  chert  deposits  are  of  two  kinds,  first,  creek  gravel,  and 
second,   residual   accumulations   upon  the   outcrop   of   the   Osage   formation. 

To  a  depth  of  six  to  ten  feet  or  perhaps  more  in  places,  the  creek  gravel 
underlies  the  flood-plain  areas  along  the  streams  heading  near  the  Hicks 
dome,  as  Hicks  Branch,  its  north  fork,  and  Goose  Creek.  Such  material  too, 
is  present  in  abundance  along  Big  Creek  and  Hogthief  Creek  in  the  northern 
part  of  the  county.  It  usually  has  a  cover  of  alluvium  two  or  more  feet  in 
thickness.  The  residual  mantle  on  the  outcrop  of  the  Osage  is  of  greatly 
varying  thickness;  on  the  ridge  tops  it  is  probably  not  very  deep,  but  on  the 
sides  of  the  hills,  especially  towards  the  bottoms  of  the  slopes,  there  must 
be  very  large  bodies  of  rock  waste  made  up  largely  of  angular  fragments  of 
chert  mingled  with  a  greater  or  less  proportion  of  earth.  Including  both 
kinds  of  deposits  there  seems  to  be  an  almost  inexhaustible  quantity  of  ma- 
terial, especially  when  it  is  remembered  that  not  improbably  the  solid  chert 
of  the  ridges  is  minutely  divided  by  joints  and  would  easily  break  up  in 
quarrying  into  small  pieces  suitable  for  road  metal.  Chert  beds  of  similar 
character  and  age  in  the  vicinity  of  Birmingham,  Alabama,  do  break  up  thus 
in  quarrying  and  need  hardly  any  further  preparation  for  road  work.  All  of 
the  creek  gravel  and  residual  material  on  the  ridges  could  be  raised  by  steam 
shovel  and  screened  to  suitable  sizes  for  the  different  courses  of  a  macadam 
road,  and  all  would  be  ready  for  use  with  this  preparation  alone,  except  that 
the  finer  screenings  for  the  top  surface  might  need  a  small  admixture  of 
finely  crushed  limestone  for  binding  material. 

No  tests  of  this  material  have  been  made,  either  in  actual  use  or  in  the 
laboratory,  but  in  a  few  places  where  roads  are  located  upon  it  on  the  ridges 
or  for  short  distances  in  the  valleys  near  the  base  of  the  ridges,  the  excellent 
effects  of  the  material  in  maintaining  a  hard,  smooth  surface  on  the  road  are 
amply  demonstrated.  The  excellence  of  such  material  is  also  shown  by  the 
roads  surfaced  with  it  about  Birmingham  and  Bessemer,  Alabama.  The 
building  of  one  of  the  new  state  roads  which  will  pass  near  an  easy  supply 
of  this  material,  will  present  an  opportunity  for  testing  it  that  should  not 
be  missed.  If  it  should  prove  as  good  as  it  is  believed  to  be,  the  material 
might  find  a  very  extensive  use  in  southern  Illinois,  for  the  Hicks  region  is 
the  nearest  source  of  supply  of  such  good  road  material  to  a  large  territory. 

OIL    AND    GAS    POSSIBILITIES 
STRUCTURE 

The  structural  features  in  northwestern  Hardin  County  include  from 
southeast  to  northwest  the  Hicks  anticline,  the  Eagle  Valley  syncline,  the 
Horton  Hill  anticline,  the  Potato  Hill  syncline,  and  the  Bald  Hill  anticline. 

The  Hicks  anticline  is  a  strong  fold  long  known  as  the  Hicks  dome; 
farther  northwest,  mainly  in  southeast  Saline  County  but  extending  south- 
westward  into  northern   Pope   County,   is  a  low  oval  anticline  here  named 


308  GEOLOGY    OF   HARDIN    COUNTY 

the  Horton  Hill  anticline;  and  a  mile  or  two  still  farther  west  is  a  strong 
unsymmetrical  anticline,  extending  from  Lusk  Creek  in  sec.  24,  T.  11  S., 
R,  6  E.,  northeastward  through  Bald  Hill,  and  hence  called  the  Bald  Hill 
anticline. 

The  form  and  extent  of  the  Hicks  dome  and  of  the  Horton  Hill  anti- 
cline are  shown  on  the  accompanying  map  (PL  III)  by  structure  contours, 
those  on  the  Hicks  dome  being  drawn  on  the  top  of  the  black  Chattanooga 
shale  at  vertical  intervals  of  100  feet,  and  those  on  the  Horton  Hill  anti- 
cline drawn  on  the  top  of  the  Palestine  sandstone  at  vertical  intervals  of  50 
feet.  Only  the  approximate  position  of  the  axis  of  the  Bald  Hill  anticline  is 
indicated,  owing  to  its  narrowness,  steep  northwest  limb,  and  less  well-known 
details. 

Between  the  Hicks  dome  and  the  Horton  Hill  anticline  is  the  Herod 
fault  and  a  syncline  provisionally  named  the  Eagle  Valley  syncline.  The 
Herod  fault  trends  northeast,  and  the  strata  are  downthrown  on  the  south- 
east side  about  100  to  200  feet.  Between  the  Horton  Hill  and  Bald  Hill 
anticlines  is  the  Potato  Hill  syncline,  the  axis  of  which  lies  near  and  just 
west  of  Potato  Hill  in  the  SW.  %  sec.  18,  T.  11  S.,  E.  7  E. 

Two  faults  cut  into  the  northeast  flank  of  the  Hicks  Dome  and  the 
most  southeasterly  one  may  pass  across  the  dome.  About  2  miles  farther 
southeast,  and  outside  of  the  area  mapped,  another  fault  cuts  across  the 
Hicks  anticline  in  a  general  northeast-southwest  direction  like  the  mapped 
faults. 

From  the  center  of  the  Hicks  dome  the  rocks  dip  outward  strongly 
to  the  southwest  and  northeast  and  intermediate  directions  with  dips  be- 
tween 10  and  20  degrees;  the  dip  is  more  gentle  to  the  southeast.  In  broad 
areas  to  the  southwest  and  to  the  north  of  the  center  of  the  dome,  the 
dip  is  low  or  the  strata  are  nearly  fiat.  This  flattening  of  the  structure, 
producing  a  structural  terrace,  is  indicated  by  the  spreading  of  the  con- 
tour lines  in  sees.  13,  34,  and  35,  T.  11  S.,  R.  7  E. ;  sees.  2  and  3,  T.  12  S.,  R, 
7  E,  and  sees.  17  and  18,  T.  11  S.,  R.  8  E.  Outward  from  these  terraces  the 
dip  steepens  to  about  10  degrees  which  prevails  to  the  outer  margin  of  the 
contoured  area  southeast  of  the  Herod  fault.  Beyond  the  contoured  area 
the  rocks  dip  at  angles  less  than  5  degrees  as  far  as  the  axis  of  the  Eagle  j 
Valley  cyncline,  but  the  continuity  of  the  strata  is  interrupted  by  the  Herod 
fault. 

West  of  the  Eagle  Valley  axis  the  strata  rise  westward  at  a  small  de- 
gree to  the  axis  of  the  Horton  Hill  anticline.  This  seems  to  be  an  elong- 
ated dome,  the  axis  of  which  pitches  moderately  to  the  northeast  and  to 
the  southwest  from  the  center  of  the  dome.  'Northwest  of  this  axis  the 
rocks  dip  northwestward  at  a  low  angle  to  the  axis  of  the  Potato  Hill  syn- 
cline. From  the  last  named  axis  the  strata  rise  westward  to  the  axis  of 
the  Bald  Hill  anticline  at  a  rate  gradually  increasing  to  as  much  as  25  de- 


ECONOMIC   GEOLOGY  309 

grees,  locally,  near  the  axis.  Immediately  west  of  the  axis  the  dip  varies 
from  15  to  60  degrees  westward,  the  steeper  dips  being  observed  in  sees. 
12  and  13,  T.  11  S.,  K  6  E.  and  in  sec.  31,  T.  10  S.,  R.  7  E.  A  short 
distance  west  of  the  axis  the  rocks  are  nearly  horizontal. 

POSSIBLE  OIL-BEARING   STRATA 

In  the  central  part  of  the  Hicks  dome  the  possible  sources  of  oil  lie 
below  the  Devonian  limestone.  Of  these  lower  strata  nothing  directly  is 
known  in  the  region,  since  they  are  nowhere  exposed  at  the  surface  and 
have  not  been  penetrated  by  deep  wells.  Rocks  that  normally  occupy  this 
stratigraphic  position  outcrop  in  Union  and  Alexander  counties,  111.,  50  miles 
west  of  Hardin  County;  and  along  Tennessee  River  70  miles  and  farther 
south  of  the  region.  From  the  Devonian  and  Silurian  rocks  of  these  regions 
must  be  inferred  the  possible  character  of  the  corresponding  part  of  the 
general  geologic  column  in  Hardin  County.  According  to  Savage1,  in  Union 
and  Alexander  counties  these  rocks  include  limestone  of  Onondaga  age  150 
feet  thick,  sandstones  and  cherty  limestone  of  Oriskany  age  235  feet  thick 
immediately  underlying  the  Onondaga  limestone  of  Illinois  reports,  limestone 
of  Heldei bergian  age  160  feet  thick;  limestones  of  Silurian  age  120  feet; 
and  sandstone  of  Richmond  age,  the  Thebes  sandstone  of  Illinois  reports,  90 
feet  thick,  lying  about  530  feet  below  the  limestone  of  Onondaga  age.  If 
the  section  of  these  lower  strata  in  Hardin  County  is  at  all  like  what  it  is  in 
Union  County,  it  is  possible  that  some  of  these  sandstone  beds  underlie  the 
Hicks  dome  at  a  depth  of  not  over  1,000  feet  below  the  top  of  the  Chattanooga 
shale.  These  strata  are  nowhere  known  to  be  oiJ -bearing,  but  that  is  not 
necessarily  a  condemnation,  for  in  the  Colmar  field  in  McDonough  County, 
111.,  the  oil  is  in  a  local  sand  of  Niagaran  age,  and  in  Allen  County,  Ky.,  the 
oil  is  reputed  to  be  in  rock  of  Niagaran  age.  These  are  recent  discoveries  and 
apparently  the  only  occurrences  of  the  kind.  There  is  always  a  chance  of  oil 
occurring  at  horizons  at  which  it  has  not  been  found  elsewhere. 

Farther  out  from  the  center  of  the  Hicks  dome,  as  on  the  structural 
terraces  previously  mentioned,  there  is,  in  addition  to  the  chance  of  oil  in 
the  strata  below  the  Devonian  limestone,  the  chance  of  its  presence  in  that 
limestone  itself,  strata  of  that  age  being  oil-bearing  in  the  Irvine  field  in 
eastern  Kentucky,  in  the  field  in  Ohio  County,  Ky.,  and  in  the  oil  fields  of 
Ontario,  Canada.  The  lower  part  of  the  limestone  of  Onondaga  age  in 
Union  County,  111.,  is  said  to  have  a  strong  odor  of  petroleum.  The  top  of 
this  limestone  should  be  reached  at  about  1,600  feet  below  the  general  level 
of  the  country  in  the  area  of  the  structural  terraces  in  sees.  13,  34,  and  35, 
T.  11  S.,  R.  7  E,;  sees.  2  and  3,  T.  12  S.,  R.  7  E. ;  and  sec.  17,  T.  11  S.,  R.  8 
E.;   and   the   possibly   oil-bearing   strata   below   the   limestone   are  probably 

1  Savage,    T.    E.,    Lower   Paleozoic    stratigraphy   of   southwestern    Illinois:      111.    State 
Geo.  Survey,  Bull.   8,  pp.  103-116,  1907. 


310  GEOLOGY    OF   HARDIN    COUNTY 

within  a  depth  of  2,200  feet  below  the  general  level  of  the  ground  in  these 
sections. 

In  the  region  of  the  Horton  Hill  anticline  there  is  also  a  chance  that 
the  basal  sandstone  strata  of  the  Chester  group  may  contain  oil.  The  top 
of  these  sandstones  is  at  a  depth  of  500  to  GOO  feet  along  the  Horton  Hill 
axis,  whereas  the  limestone  of  Onondaga  age  is  probably  about  2,300  feet 
deep  and  the  horizon  of  the  Thebes  sandstone  of  the  Illinois  Survey,  the 
lowest  possible  sandstone,  is  probably  not  over  3,000  feet  below  the  top 
of  the  upper  Chester  sandstone  in  the  center  of  the  anticlinal  area. 


PART  VI 
PALEONTOLOGY 


CHAPTER  XIII— PALEONTOLOGY 

By  Stuart  Weller 

In  each  of  the  several  chapters  of  the  stratigraphic  portion  of  this  report, 
a  section  has  been  devoted  to  the  paleontology  of  the  formations  described. 
These  discussions  have  been  confined  to  a  consideration  of  the  general  char- 
acteristics of  the  faunas  of  the  formations,  especially  in  the  consideration  of 
the  bearing  of  the  faunas  upon  their  correlation,  and  no  technical  descriptions 
of  any  of  the  fossils  have  been  given.  In  the  course  of  the  work,  however,  it 
has  developed  that  certain  of  the  fossils  need  further  description  and  discus- 
sion. Some  of  these  are  undescribed  forms  which  have  some  direct  bearing 
upon  the  questions  of  correlation,  and  must  therefore  be  defined  for  the  first 
time.  Others  are  species  which  are  already  named  but  which  have  some 
special  bearing  upon  questions  which  are  discussed  in  the  report,  and  which 
need  further  illustration  and  consideration.  No  attempt  will  be  made  here 
to  include  descriptions  of  all  of  the  fossil  species  known  to  occur  in  the  rock 
strata  of  Hardin  County,  for  such  a  treatment  would  require  a  large  volume. 
Most  of  the  species  that  will  be  discussed  in  this  chapter  are  members  of  some 
one  or  another  of  the  Chester  faunas,  although  only  a  small  number  of  the 
Chester  forms  as  a  whole  are  considered.  , 

In  the  selection  of  species  for  discussion  in  this  chapter  a  special  effort 
has  been  made  to  choose  those  which  have  a  direct  bearing  upon  certain  ques- 
tions of  correlation  concerning  which  some  differences  of  opinion  have  de- 
veloped. The  differences  center  around  the  correlation  of  the  Renault  and 
Golconda  limestones.  In  considering  the  questions  connected  with  the  corre- 
lation of  the  Renault,  certain  Ste.  Genevieve  and  even  St.  Louis  limestone 
species  have  to  be  discussed,  as  well  as  a  few  from  the  Paint  Creek  formation, 
and  all  of  these  will  be  grouped  together  as  "Lower  Chester  and  related 
species/'  The  consideration  of  the  correlation  of  the  Golconda  limestone 
involves  a  comparison  of  species  common  to  the  Golconda  and  the  Lower 
Okaw  limestone  of  Randolph  County,  and  these  forms  will  be  discussed  under 
the  heading  "Golconda  and  Lower  Okaw  species." 

In  addition  to  these  two  groups  of  species  which  will  be  treated  in  the 
following  pages,  a  number  of  "Miscellaneous  Chester  Species"  will  also  be 
considered.  These  are  species  which  are  particularly  characteristic  of  some 
one  of  the  Chester  formations,  and  which  either  have  been  inadequately 
described  in  earlier  literature  or  need  some  further  treatment. 

313 


314  GEOLOGY  OF  HARDIN  COUNTY 

LOWES  CHESTER  AND  RELATED  SPECIES 

Amplexus  geniculatus  Worthen 

Plate  V,  Figs.  31-33 
.1890.     Amplexus  geniculatus  Worthen,  Geol.  Surv.  111.,  vol.  8,  p.  82,  pi.  10, 

figs.  7-7a. 
1905.  Amplexus  geniculatus  Ulrich,  U.  S.  Geol.  Surv.  Prof.  Paper  No.  36, 
p.  47,  pi.  5,  figs.  15a-d. 
This  little  coral,  one  of  the  best  index  fossils  of  the  Shetlerville  forma- 
tion, is  so  characteristic  that  the  faunal  zone  of  the  Shetlerville  has  been 
referred  to  in  the  foregoing  pages  as  the  Amplexus  geniculatus  zone.  The 
species  is  characterized  by  its  slightly  tapering,  almost  cylindrical  form,  and 
not  infrequently  the  specimens  show  abrupt,  geniculate  bends,  as  in  figure  32 
of  the  accompanying  plate. 

Horizon  and  locality. — Shetlerville  formation,  Hardin   County,  Illinois, 
and  Crittenden  County,  Kentucky.     Lower  Chester,  Union  County,  Illinois. 

Pentremites  princetonensis  Ulrich 

Plate  IV,  Figs.  1-7 
1905.     Pentremites  florealis    (part)    Ulrich,  U.   S.   Geol.   Surv.  Prof.   Paper 

No.  36,  p.  58,  pi.  6,  figs.  18  a,  c  (not  figs.  18  b,  d-f). 
1918.     Pentremites  princetonensis  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West. 

Ky.,  p.  243,  pi.  2,  figs.  8-14.      (Name  and  illustrations  published 

without  description.) 
Description. — Body  small,  subovate  to  sub-bipyramidal  in  form,  higher 
than  wide,  the  greatest  width  at  the  bases  of  the  ambulacra.  The  dimensions 
of  two  nearly  perfect  specimens  are:  height  11.6  mm.,  and  9.9  mm.,  greatest 
width  9  mm.  and  7.2  mm.,  length  of  ambulacra  7.8  mm.  and  5.8  mm. 
Dorsal  region  of  the  body,  below  the  ends  of  the  ambulacra,  obpyramidal  in 
form,  the  five  faces  flat  or  very  slightly  concave  in  transverse  direction,  be- 
coming slightly  subpedunculate  at  the  extreme  base,  with  the  apex  of  the 
pyramid  truncated  for  the  stem  attachment;  the  basal  plates  occupying  about 
one-half  or  less  than  one-half  the  distance  from  the  stem  facet  to  the  ends 
of  the  ambulacra;  the  five  angles  separating  the  faces  of  the  dorsal  pyramid 
are  narrowly  rounded  and  become  much  more  prominent  as  they  approach 
the  ambulacral  extremities.  The  ventral  region,  from  the  ends  of  the  am- 
bulacra to  the  summit,  with  converging  profile,  the  sides  becoming  increasingly 
convex  towards  the  summit  which  is  truncate.  Ambulacra  very  gently  convex 
with  a  distinct  median  groove,  each  of  the  two  sides  convex  with  the  slope  to 
the  median  groove  short  and  abrupt,  while  that  to  the  lateral  margins  is  long 
and  gentle ;  the  side-plates  eleven  or  twelve  in  the  space  of  3  mm.  The  inter- 
ambulacral  areas  gently  concave.     The  deltoid  plates  one-half  or  less  than  one- 


PALEONTOLOGY  31 5 

half  the  length  of  the  ambulacra,  their  dorsal  margins  meeting  at  the  middle 
line  in  an  angle  less  than  a  right  angle. 

Remarks. — Among  the  specimens  of  Pentre mites  from  the  Fredonia 
limestone  and  the  "Upper  Ohara"  limestone  of  Ulrich,  which  might  be  re- 
ferred to  the  species  P.  princetonensis,  there  are  three  rather  distinct  types 
which  may  be  separated,  although  intergrading  examples  may  be  found  which 
serve  to  connect  the  three  forms.  Ulrich  referred  all  three  of  these  forms  to 
P.  florealis  in  19051  but  in  his  recent  Kentucky  report  he  has  distinguished 
them  as  three  different  species,  P.  princetonensis,  P.  pulchelhis,  and  P. 
pinguis.  He  has  published  no  descriptions  of  any  of  the  species,  and  in  the 
case  of  P.  princetonensis  the  holotype  is  not  indicated  among  the  specimens 
illustrated. 

Considering  the  first  of  the  figures  designated  by  the  name  P.  prince- 
tonensis in  the  Kentucky  report,  (fig.  8  on  plate  2)  as  the  holotype,  this 
name  may  be  applied  to  those  specimens  with  the  deeper  dorsal  region  which 
is  obpyramiclal  in  form.  The  more  elongate  specimens  with  proportionately 
shallower  dorsal  region  constitute  the  species  called  P.  pulchellus,  and  the 
shorter  and  broader  specimens  with  more  nearly  flat  dorsum  are  P.  pinguis 
The  great  variability  of  all  these  forms  is  shown  in  the  fact  that  among  the 
original  illustrations  of  the  species  there  is  greater  difference  shown  among 
specimens  that  are  designated  by  the  same  name  than  between  certain  of  the 
specimens  that  are  referred  to  different  species.  For  instance,  figures  6  and  7 
of  Ulrich's  Plate  2,  called  P.  pulchelhis,  are  much  more  like  figures  8  and  9 
that  are  called  P.  princetonensis,  than  they  are  like  the  specimen  designated 
as  the  holotype  of  P.  ptdchellus. 

A  critical  examination  of  many  hundreds  of  specimens  of  these  pentre- 
mites  has  brought  out  certain  features  which  are  of  value  for  stratigraphic 
purposes.  The  typical  P.  princetonensis,  with  its  obpyramidal  dorsum  is 
most  widely  distributed  in  the  Fredonia  limestone  of  Ohio  Valley  and  in  the 
typical  Ste.  Genevieve  limestone  of  Mississippi  Valley.  It  is  also  present  in 
its  typical  form  in  the  St.  Louis  limestone,  although  all  pentremites  are  rare 
in  that  horizon,  and  neither  of  the  other  two  forms  have  been  recosmized 
there.  It  continues  upward  into  the  Shetlerville,  and  is  locally  present  in 
the  Eenault.  Pentremites  pnxlchellus  is  common  in  the  Fredonia  and  in  the 
Shetlerville  and  may  be  present  in  the  .Renault,  but  it  is  not  a  conspicuous 
member  of  that  fauna.  P.  pinguis  occurs  in  great  numbers  in  the  Shetlerville 
and  is  common  in  the  Eenault,  but  is  much  less  common  in  the  Fredonia. 

Ulrich  has  used  these  three  forms  in  his  attempt  to  establish  the  fauna! 
connection  between  the  Fredonia  and  the  uUpper  Ohara,"  both  of  which  he 
places  in  the  Ste.  Genevieve  limestone,  but  P.  princetonensis  connects  the 
Fredonia  fauna  with  that  of  the  St.  Louis  limestone  as  closely  as  or  more 
closely  than  the  connection  with  the  higher  beds.     The  whole  situation  is 

1  Prof.  Paper,  U.  S.  Geol.   Surv.,   No.   36,  pi.   6,   figs.   18a-f. 


316  GEOLOGY   OF    HARDIN    COUNTY 

one  which  shows  the  folly  of  attempting  to  establish  faunal  relationships  and 
correlation  upon  single  fossil  forms.  The  true  faunal  relations  must  he 
established  through  a  critical  examination  of  the  whole  fauna,  and  when  this 
is  done  it  leaves  no  basis  whatsoever  for  associating  the  "Upper  Ohara"  with 
the  Ste.  Genevieve  limestone. 

Formation  and  locality. — St.  Louis  limestone,  St.  Louis,  Missouri,  and 
above  Little  Rock,  Ste.  Genevieve  County,  Missouri ;  Ste.  Genevieve  limestone, 
Fountain  Creek,  Monroe  County,  Illinois,  and  Ste.  Genevieve  County,  Mis- 
souri; Fredonia  limestone,  Cedar  Bluff  quarry,  near  Princeton,  Kentucky, 
and  Rosiclare,  Illinois;  Shetlerville  formation,  Fairview  bluff,  Hardin 
County,  Illinois,  and  elsewhere;  Renault  formation,  Johnson  County,  Illinois, 
and  elsewhere. 

Pentremites  pulchellus  Ulrich 

Plate  IV,  Figs.  14,  28-30 
1905.     Pentremites  florealis  (part)   Ulrich,  U.  S.  Geol.  Surv.,  Prof.  Paper 

No.  36,  p.  58,  pi.  6,  figs.  18  b,  d  (not  figs.  18a,  c,  e-f). 
1918.     Pentremites  pulchellus  Ulrich,  Geol.   Surv.  Ky.,  Miss.  Form.  West. 

Ky.,  pi.   2,  figs.   1-7.      (Name  and  illustrations  published  without 

description.) 
Description. — Body  small,  elongate  subovate  in  form,  much  higher  than 
wide,  the  greatest  width  at  or  a  little  above  the  bases  of  the  ambulacra.  The 
dimensions  of  a  practically  perfect  individual  are:  height  15  mm.,  greatest 
width  10  mm.,  length  of  ambulacra  7.7  mm.,  greatest  width  of  ambulacra  2.9 
mm.  Dorsal  region  of  the  body,  below  the  ends  of  the  ambulacra,  with  the 
sides  sloping  inward  to  the  stem  facet,  the  profile  nearly  straight  distally, 
becoming  concavely  curved  as  it  approaches  the  base;  subpedunculate,  and 
truncated  for  the  stem  attachment;  five  shoulder-like  elevations  pass  from 
the  base  to  the  extremities  of  the  ambulacra,  becoming  more  strongly  raised 
distally ;  the  interambulacral  surfaces  between  gently  concave ;  the  basal  plates 
reaching  about  half  way  from  the  stem  facet  to  the  extremities  of  the  am- 
bulacra. Ventral  region  of  the  body,  from  the  ends  of  the  ambulacra  to  the 
summit,  very  much  higher  than  the  dorsal  region,  the  sides  converging 
towards  the  summit,  the  convergence  gentle  below,  becoming  more  abrupt 
towards  the  summit,  giving  to  the  sides  a  convex  profile  which  becomes  more 
strongly  curved  above.  Ambulacra  very  gently  convex  or  nearly  flat,  with  a 
shallow  median  groove,  the  lateral  surfaces  with  a  very  short,  rather  abrupt 
slope  to  the  groove  and  a  long  gentle  slope  to  the  lateral  margins;  the  lateral 
grooves  9  or  10  in  the  space  of  three  millimeters,  directed  transversely  at  the 
summit,  becoming  progressively  more  oblique  towards  the  distal  extremity 
of  the  ambulacra  where  they  are  directed  upward  as  they  approach  the  median 
groove.      Interambulacral    areas   gently   concave   transversely,   the   concavity 


PALEONTOLOGY  317 

becoming  more  abrupt  ventrally  because  of  the  slightly  raised  lateral  margins ; 
deltoid  plates  longer  than  wide,  but  less  than  half  the  length  of  the  ambulacra, 
the  basal  margins  meeting  at  the  middle  of  the  interambulacral  area  in  an 
angle  of  less  than  90°.  On  well-preserved  specimens  the  surface  of  the  radial 
and  deltoid  plates  is  marked  by  exceedingly  fine,  regular  lines  running  parallel 
with  the  margins,  the  oblique  lines  on  the  radials  which  are  parallel  with  the 
radio-deltoid  sutures  being  stronger  and  somewhat  more  rugose  than  the 
longitudinal  lines  upon  the  same  plates. 

Remarks. — The  above  description  of  this  species  has  been  drawn  up  from 
specimens  collected  from  the  Fredonia  limestone  near  Princeton,  Kentucky, 
which  agree  very  closely  with  figures  1,  2,  and  3  of  Ulrich's  illustrations, 
figure  2  being  designated  as  the  holotype.  Ulricas  illustrations  exhibit  a 
considerable  amount  of  variation  and  include  figures  of  specimens  from  the 
"Upper  Ohara"  limestone  as  well  as  from  the  Fredonia.  In  some  of  the 
figures  the  basal  profile  shows  much  less  concavity  than  the  more  typical 
examples,  the  lines  being  nearly  straight,  and  his  figures  6  and  7,  especially 
7,  really  resemble  his  illustrations  of  P.  princetonensis  more  closely  than  they 
do  that  of  the  holotype  of  the  species.  The  ambulacra  are  perhaps  a  little 
flatter  in  the  typical  princetonensis  than  in  pulchellus,  but  in  a  large  collec- 
tion of  hundreds  of  specimens  from  the  Shetlerville  division  of  the  "Upper 
Ohara,"  it  is  possible  to  find  every  gradation  between  the  two  forms.  The 
specimens  from  the  Shetlerville  formation  that  are  referred  to  the  species 
have  a  distinctly  shallower  dorsal  region  than  do  those  from  the  Ste.  Genevieve. 

Horizon  and  locality. — Fredonia  limestone,  Cedar  Bluff  quarry,  near 
Princeton,  Kentucky,  and  Rosiclare,  Illinois.  Shetlerville  formation,  Fair- 
view  bluff,  Hardin  County,  Illinois,  and  elsewhere. 

Pentremites  pingtjis  Ulrich 

Plate  IV,  Figs.  8-12 
1905.     Pentremites  fiorealis  (part)   Ulrich,  U.  S.  Geol.  Surv.,  Prof.  Paper 

No.  36,  p.  58,  pi.  6,  figs.  18  e-f,  (not  figs.  18  a-d). 
1918.     Pentremites  pinguis  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West.  Ky., 
p.  244,  pi.  2,  figs.  16-17.     (Fame  and  illustrations  published  with- 
out description.) 
Description. — Body  of  medium  size  or  smaller,  subovate  in  form,  higher 
than  wide,  the  greatest  width  at  or  very  near  the  bases  of  the  ambulacra.    The 
dimensions  of  a  very  complete  specimen  are:  height  11.9  mm.,  greatest  width 
9.5  mm.,  length  of  ambulacra  9  mm.,  greatest  width  of  ambulacra  3  mm. 
Dorsal  region  of  the  body,  below  the  ends  of  the  ambulacra,  sloping  inward 
nearly  to  the  point  of  attachment  of  the  stem,  with  a  straight  or  slightly 
concave  profile,  the  extreme  basal  extremity  slightly  produced  or  subpedun- 
culate,  the  basal  plates  occupying  about  one-half  the  distance  from  the  stem 


318  GEOLOGY    OF    HARDIN"    COUNTY 

facet  to  the  base  of  the  ambulacra;  five  shoulder-like  elevations  extending 
from  the  base  to  the  extremities  of  the  ambulacra,  becoming  more  strongly 
raised  distally,  the  interambulacral  surfaces  flat  or  slightly  concave.  Ventral 
region  of  the  bod)-,  from  the  ends  of  the  ambulacra  to  the  summit,  with  the 
sides  gently  convex  and  converging  to  the  subtruncate  summit.  Ambulacra 
nearly  flat,  with  a  shallow  median  groove,  the  two  sides  very  gently  convex 
with  the  curvature  a  little  more  abrupt  to  the  median  groove ;  the  side  plates 
about  ten  in  the  space  of  3  mm.  Interambulacral  areas  transversely  a  little 
concave  in  well  preserved  specimens,  the  margins  slightly  elevated  into  low, 
keel-like,  bordering  ridges  in  the  ventral  half,  the  elevations  on  the  two  sides 
joining  at  the  apex  of  the  deltoid  plates,  below  which  there  is  a  slight  de- 
pression. Deltoid  plates  somewhat  variable,  more  or  less  than  one-half  the 
length  of  the  ambulacra,  their  dorsal  margins  slightly  curved.,  and  meeting 
at  the  dorsal  apex  in  an  angle  varying  from  considerably  less  to  more  than 
90°. 

Remarks. — Among  the  six  specimens  illustrated  by  Ulrich  in  1905  and 
referred  to  Pentremites  florealis1,  the  two  shorter  and  broader  ones  with  the 
flatter  dorsal  region,  have  been  referred  to  the  new  species  P.  pinguis  in  his  re- 
cent Kentucky  report.  These  two  specimens,  illustrated  in  the  earlier  report, 
really  represent  a  very  abundant  pentremite  of  the  Shetlerville  fauna  of 
Hardin  County  and  elsewhere,  better  than  does  the  specimen  designated  as 
holotype  of  the  species  in  the  recent  Kentucky  report.  Since  the  name 
P.  florealis  has  no  standing  whatsoever,  if  the  form  is  to  be  recognized  as  a 
species,  Ulricrr's  newly  proposed  name  is  as  good  as  any,  although  no  descrip- 
tion of  it  has  been  published.  Among  the  mairy  hundreds  of  specimens  of 
pentremites  from  the  Shetlerville  formation  that  have  been  examined,  com- 
plete gradations  may  be  selected  which  connect  this  form  with  both  P.  prince- 
tonensis  and  P.  pidcliellus,  and  doubtless  some  observers  would  hesitate  to 
consider  these  forms  as  anything  more  than  varieties  of  a  single  species.  Some 
names  seem  to  be  desirable,  however,  for  the  different  forms,  especially  as 
they  really  have  some  stratigraphic  value.  P.  princetonensis  is  more  com- 
monly represented  in  the  St.  Louis  and  Ste.  Genevieve  limestones,  but  is  not 
restricted  to  these  horizons.  P.  pttlchellus  is  best  represented  in  the  Ste. 
Genevieve  and  Shetlerville,  while  P.  pinguis  occurs  most  abundantly  in  the 
Shetlerville  and  Eenault.  On  plate  IV,  examples  of  this  species  from  the 
"Upper  Ohara"  of  Hardin  County,  and  the  Renault  limestone  of  Monroe 
County,  are  illustrated  side  by  side  in  order  to  show  their  identity. 

Pentremites  pinguis  is  one  of  the  commoner  species  in  the  Renault  of 
Hardin  County,  but  it  is  associated  with  several  other  forms,  among  which  is 
the  earliest  known  of  the  "pyriform"  types  of  the  genus,  this  association  being 
identical  with  that  found  in  the  typical  Renault  of  Monroe  and  Randolph 
counties,  and  the  same  "pyrifornr"  species  occurs  in  both  regions. 

1  LT.   S.   Geol.   Surv.,  Prof.   Paper,  No.  36,  pi.   6,   figs.  18a-f. 


PALEONTOLOGY  319 

Horizon  and  locality. — Shetlerville  formation,  Fairview  bluff,  Hardin 
County,  Illinois,  and  elsewhere.  Renault  limestone,  Hardin,  Monroe,  and 
Randolph  counties,  Illinois. 

Pentremites  godoni  (Def ranee) 

Plate  IV,  Figs.  31-36,  47 
1808.     "An  asterial  fossil,"   Parkinson,   Org.   Rem.,  vol.   2,  p.   235,  pi.   13, 
figs.  36-37. 

1819.  Encrina  Godoni  Defrance,  Diet.  Sci.  Nat.,  vol.  1-1,  p.  469. 

1820.  Encrinites  florealis  von  Schlotheim,  Petrefactenkunde,  vol.   2,  p.  38. 
1918.     Pentremites  planus  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West.  Ky., 

pi.  5,  figs.  1-13.  (Name  and  illustrations  published  without  de- 
scription.) 
Description. — Body  of  medium  size,  subovate  in  form,  the  height  and 
width  subequal  or  higher  than  wide ;  an  occasional  example  wider  than  high, 
the  greatest  width  at  or  a  little  above  the  ends  of  the  ambulacra.  The  dimen- 
sions of  a  practically  perfect  specimen  are:  height  16.6  mm.,  greatest  width 
14.5  mm.,  length  of  ambulacra  14  mm.,  greatest  width  of  ambulacra  4.4  mm. 
Dorsal  region  of  the  body,  below  the  ends  of  the  ambulacra,  very  short,  in 
some  examples  nearly  flat,  with  a  short,  slightly  projecting,  subpedunculate 
central  region;  in  profile  the  slopes  from  the  ambulacral  extremities  to  the 
central  projection  nearly  straight  or  gently  concave,  in  some  examples  the 
•curvature  being  slightly  interrupted  near  the  middle;  between  the  lower 
extremities  of  the  ambulacra  and  the  center  of  the  base,  the  dorsal  surface  is 
raised  into  five  shoulder-like  ridges  which  become  nearly  or  quite  obsolete 
about  half  way  to  the  stem  facet,  the  interambulacral  surfaces  between  these 
ridges  being  gently  concave  towards  the  outer  border;  the  basal  plates  reach- 
ing about  half  way  from  the  center  of  the  dorsal  surface  to  the  lower  extremi- 
ties of  the  ambulacra.  Ventral  region  of  the  body,  from  the  ends  of  the 
ambulacra  to  the  summit,  much  higher  than  the  dorsal  region,  the  sides 
converging  towards  the  summit  with  a  gentle  convex  curvature  which  in- 
creases above.  The  ambulacra  nearly  flat  transversely  towards  the  summit, 
becoming  gently  convex  towards  the  lower  extremities,  with  a  shallow  median 
groove;  the  lateral  grooves  7  to  10  in  the  space  of  three  millimeters,  situated 
transversely  towards  the  summit,  becoming  progressively  more  oblique 
towards  the  lower  end  of  the  ambulacra,  where  their  inner  extremities  are 
slightly  curved  and  directed  towards  the  summit.  Interambulacral  areas 
gently  concave  transversely,  with  their  margins  somewhat  abruptly  elevated, 
this  elevation  becoming  progressively  more  pronounced  in  a  ventral  direction, 
in  some  examples  being  elevated  in  an  almost  knife-like  edge  along  the  sides 
of  the  deltoid  plates.  The  deltoid  plates  a  little  less  than  half  the  length  of 
the  ambulacra,  their  dorsal  margins  straight  or  convexly  curved,  and  meeting 
in  the  center  of  the  interambulacral  area  in  an  angle  of  more  or  less  than  90°. 


320  GEOLOGY    OF    HARDIN    COUNTY 

Remarks. — In  its  immature  condition  this  species  is  essentially  indis- 
tinguishable from  P.  pinguis,  except  that  the  ambulacra  are  perhaps  slightly 
flatter  towards  the  summit  in  most  individuals.  These  immature  examples 
have  the  dorsal  region  proportionally  deeper  than  in  the  mature  specimens, 
and  the  similarity  of  this  species  through  its  young  individuals  with  P. 
pinguis,  is  such  as  to  leave  no  doubt  regarding  the  genetic  relations  of  the 
two  species. 

Pentremites  godoni  has  been  a  much  abused  species,  since  almost  any 
pentremite  having  a  subglobular  form  has  been  referred  to  it  by  authors. 
The  species  was  originally  based  upon  two  figures  published  by  Parkinson  in 
1808.  No  name  was  given  to  the  object  figured  by  this  author,  but  it  was 
referred  to  in  the  explanation  of  the  plate  as  "An  asterial  fossil  from  America : 
probably  of  the  nature  of  the  Encrinus/'  In  the  body  of  the  text  the  fossil 
is  described  as  follows : 

"The  nature  of  the  calcareous  fossil  represented  in  Plate  XIII  figs.  36  and  37, 
is  very  ambiguous.  I  was  favored  with  it  by  Dr.  Woodhouse,  of  Philadelphia, 
who,  avowing  his  inability  to  ascertain  anything  respecting  its  original  mode  of 
existence,  informs  me  that  it  was  obtained  from  Kentucky,  where  similar  bodies 
are  frequently  found  of  a  large  size,  and  that  they  are  there  considered  as  a 
species  of  petrified  nuts. 

"This  fossil  is  somewhat  of  a  conical  roundish  form,  the  center  of  its  base 
terminating  in  a  small  round  projection  pierced  in  its  middle,  with  a  little  open- 
ing into  the  center  of  the  fossil;  from  this  projection  the  base  extends  nearly 
horizontally  to  five  prominent  points,  between  each  of  which  exists  a  shallow 
depression.  At  the  apex  of  the  cone  five  small  openings  are  placed  at  the  angles, 
formed  by  the  meeting  of  the  lines,  which  bound  five  long  triangular  surfaces, 
which,  commencing  at  the  summit  of  the  fossil,  are  disposed  tapering,  down  the 
sides,  and  terminate  in  the  projecting  points  which  are  placed  round  the  base. 
Along  the  middle  of  each  of  these  surfaces,  a  grooved  line  passes,  from  which 
upwards  of  forty  minute  processes  on  each  side  pass  to  the  lines  which  bound 
these  surfaces  at  their  sides. 

"The  opinion  which  I  formed  on  the  first  view  of  this  fossil  was,  that  it  be- 
longed to  some  animal  approximating  to  the  encrinus.  The  central  projection  at 
its  base  has,  however,  suffered  so  much  by  friction  as  not,  I  believe,  to  show  its 
original  surface;  and  hence  it  is  impossible  to  determine  at  present  anything 
respecting  the  substance  with  which  it  was  connected  at  this  point,  or  the  kind 
of  articulation  which  was  here  employed.  It,  however,  very  nearly  resembles  the 
smaller  modiolus,  from  Ireland,  which  is  represented  on  Plate  XVII." 

The  illustration  of  this  unique  fossil  form  published  by  Parkinson,  at 
once  attracted  the  attention  of  other  students  of  fossils  in  Europe,  and  in 
1918  Defrance  gave  a  name  to  the  illustration,  calling  it  Encrina  Godoni. 
This  author  seems  to  have  had  no  specimens  of  the  fossil  for  study  or  descrip- 
tion, but  simply  gave  it  a  name  on  the  basis  of  the  illustration  that  had  been 
published  by  Parkinson.  A  year  later,  1820,  von  Schlotheim  did  the  same 
thing  that  Defrance  had  done,  gave  a  name  to  Parkinson's  illustrations,  with- 
out having  access  to  specimens  for  study,  the  name  he  applied  to  it  being 
Encrinites  florealis.     These  two  names,  therefore,  godoni  and  fiorealis,  are 


PALEONTOLOGY  321 

strictly  synonyms,  and  inasmuch  as  neither  of  the  authors  of  these  names 
seem  to  have  possessed  type  specimens  upon  which  to  base  his  species,  but 
depended  upon  Parkinson's  illustrations,  the  original  specimen  used  by 
Parkinson  must  be  considered  as  being  the  holotype  of  each  of  the  species, 
and  Parkinson's  figures  must  be  the  type  illustrations. 

In  interpreting  the  species  Pentremites  godoni,  Parkinson's  illustrations 
must  be  the  guide,  and  therefore  copies  of  these  illustrations  are  given  upon 
the  accompanying  plate.  Ulrich,  however,  has  not  followed  this  course  in 
his  interpretation  of  the  species,  but  has  arbitrarily  selected  a  form  which 
occurs  in  abundance  near  Huntsville,  Alabama,  as  representing  P.  godoni. 
There  is  no  doubt  but  that  this  Huntsville  form  has  been  called  P.  godoni  by 
many  authors,  and  it  is  not  improbable  that  Defrance  himself  would  have 
referred  such  specimens  to  the  species  if  they  had  been  in  his  hands,  but  if 
we  are  to  follow  as  great  refinement  in  separating  the  species  of  Pentremites 
as  Ulrich  has  used,  then  these  Huntsville  specimens  certainly  are  not  con- 
specific  with  Parkinson's  figures.  Among  other  differences  the  ambulacra  of 
the  form  Ulrich  has  designated  as  P.  godoni  are  broadly  V-shaped  trans- 
versely, while  the  true  P.  godoni  has  gently  convex  ambulacra.  Parkinson's 
figures  represent  much  more  accurately  the  form  for  which  Ulrich  has  pro- 
posed the  new  name  P.  planus,  and  if  his  figure  3  be  compared  with  Parkin- 
son's figure  37,  due  allowance  being  made  for  the  difference  in  method  of 
illustration,  and  the  slight  difference  in  position  of  the  specimens,  it  may  be 
seen  how  closely  alike  these  forms  are,  and  if  the  name  P.  godoni  is  to  be 
used  in  a  more  restricted  manner  than  has  been  the  usual  custom,  it  must 
be  applied  to  the  form  which  Ulrich  has  named  P.  planus. 

Among  the  collections  from  the  Chester  group  of  Illinois  that  have  been 
carefully  made  during  the  past  decade,  this  form  has  been  collected  in 
greatest  abundance  and  in  the  best  state  of  preservation  from  a  locality  in 
the  Paint  Creek  formation  on  Prairie  du  Long  Creek,  in  St.  Clair  County, 
one  and  one-half  miles  northwest  of  Floraville.  Figures  6,  7,  8,  and  9  of 
Ulrich's  series  of  illustrations  of  P.  planus,  are  from  this  locality,  and  it 
occurs  elsewhere  in  the  same  formation  in  Illinois.  Individuals  occurring 
together  in  the  same  bed  at  the  Floraville  locality,  exhibit  a  wide  range  of 
variation,  and  the  extremes  among  these  variations  would  undoubtedly  be 
considered  as  distinct  species  if  they  were  found  segregated  in  different  locali- 
ties or  in  different  horizons.  At  Floraville,  however,  the  variations  intergrade 
into  one  another  and  no  sharp  lines  of  division  can  be  drawn,  and  after  a 
long  and  critical  study  of  large  collections,  one  is  forced  to  the  conclusion 
that  they  represent  a  single  highly  variable  species,  which  the  writer  prefers 
to  call  P.  godoni  rather  than  P.  planus,  the  name  introduced  by  Ulrich.  As 
so  interpreted,  P.  godoni  is  also  present  in  the  Renault  faunas  of  Illinois,  but 
the  Renault  examples  of  the  species  are  commonly  smaller  than  those  in  the 
—21  G 


322  GEOLOGY    OF    HARDIN    COUNTY 


Paint'  Creek.  Complete  gradations  can  be  traced  from  the  typical  form  of 
P.  godoni  in  the  Paint  Creek  fauna,  through  a  number  of  forms  which 
Ulrich  has  named  and  illustrated,  into  P.  princetonensis.  It  is  not  to  be 
understood  that  the  present  writer  would  advocate  the  rejection  of  the  names 
that  Ulrich  has  proposed  as  specific  designations,  for  they  will  doubtless  be 
convenient  for  the  reference  of  certain  forms  in  the  remarkably  variable 
assemblage. 

A  study  of  many  hundreds  of  these  specimens  leads  to  the  conclusion 
that  we  have  under  consideration  an  extraordinary  plastic  genetic  group 
which  exhibits  a  wide  range  of  contemporaneous  variations,  associated  with 
progressive  mutations  which  change  with  passing  time,  neither  the  varieties 
nor  the  mutations  being  separated  by  hard  and  fast  lines.  The  entire  assemb- 
lage of  individuals  may  be  divided  into  innumerable  groups,  call  them 
varieties  or  species  as  may  seem  best,  and  a  different  grouping  is  suggested 
from  a  study  of  almost  every  separate  collection.  The  larger,  more  compre- 
hensive group  may  be  considered  as  beginning  at  least  as  early  as  Fredonia 
time,  perhaps  earlier,  although  members  of  the  genus  Pentremites  are  rare 
in  the  St.  Louis  limestone.  In  the  Fredonia  limestone  the  dominant  type 
is  the  one  called  P.  princetonensis  by  Ulrich,  although  characteristic  indi- 
viduals of  P.  pulchellus  are  associated  with  it.  Perfectly  typical  examples  of 
P.  princetonensis  are  also  known  from  the  St.  Louis  limestone.  In  the  Shet- 
lerville  and  Eenault  formations  P.  pinguis  is  one  of  the  leading  forms, 
although  perfectly  typical  examples  of  P.  pulchellus  and  P.  princetonensis 
are  also  present,  and  other  specimens  which  foreshadow  or  may  even  be  re- 
ferred to  the  typical  P.  godoni  (P.  planus  Ulrich)  are  also  present.  In  the 
Paint  Creek  fauna  we  find  the  great  development  of  the  typical  P.  godoni. 
A  continuation  of  the  same  genetic  line  is  met  with  in  the  Golconda  limestone, 
although  in  the  middle  and  upper  Chester  faunas  many  quite  different  types 
of  Pentremites  make  their  appearance. 

For  purposes  of  correlation  it  is  important  to  take  cognizance  of  the 
fact  that  the  same  stage  of  development  of  this  group  of  forms  is  represented 
in  the  "Upper  Ohara"  limestone  of  Hardin  County,  and  in  the  Eenault  lime- 
stone of  Monroe  and  Eandolph  counties,  and  this  circumstance,  taken  to- 
gether with  the  fact  that  every  species  in  the  "Upper  Ohara"  faunas,  save 
about  three  that  are  wholly  restricted  to  the  Shetlerville  fauna,  are  known 
also  in  the  Eenault  faunas  of  Monroe  County  or  in  the  Paint  Creek  of  the 
same  general  region,  establishes  the  contemporaneity  of  these  two  formations 
as  firmly  as  such  contemporaneity  can  be  established  by  paleontological  evi- 
dence. 

Horizon  and  locality. — Eenault  limestone,  Monroe,  Eandolph,  and 
Hardin  counties,  Illinois.  Paint  Creek  formation,  St.  Clair,  Monroe,  and 
Eandolph  counties,  Illinois. 


PALEONTOLOGY  6X6 

Pentremites  buttsi  Ulrich 

Plate  IV,  Figs.  16-20 
1918.     Pentremites  buttsi  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West.  Ky., 
pi,  2,  figs.  18-19.      (Name  and  illustrations  published  without  de- 
scription.) 

Description. — Body  of  medium  size  or  smaller,  subpyriform,  much  higher 
than  wide,  the  greatest  width  at  the  lower  extremities  of  the  ambulacra.  The 
dimensions  of  a  nearly  perfect  specimen  are:  height  15  mm.,  greatest  width 
10  mm.,  length  of  ambulacra  9.3  mm.,  greatest  width  of  ambulacra  3.2  mm. 
Dorsal  region  of  the  body  obpyramidal,  the  slope  from  the  stem  facet  to  the 
lower  extremities  of  the  ambulacra  nearly  straight  or  very  slightly  concave; 
the  interambulacral  surfaces  of  the  dorsal  region  are  flat  or  very  slightly 
concave  transversely,  the  five  surfaces  being  separated  by  five  rounded, 
shoulder-like  ridges  which  are  best  developed  just  beneath  the  extremities  of 
the  ambulacra  and  become  nearly  obsolete  towards  the  stem  facet;  the  basal 
plates  reaching  a  little  less  than  half  way  from  the  stem  facet  to  the  bases  of 
the  ambulacra.  Ventral  region  a  little  higher  than  the  dorsal  in  mature 
individuals,  with  the  sides  nearly  straight  below  and  converging  towards  the 
summit,  curving  inward  above  to  the  subtruncate  summit.  Ambulacra  flat 
or  very  slightly  convex  transversely,  with  a  shallow  median  groove;  lateral 
grooves  seven  to  ten  in  number  in  a  space  of  three  millimeters,  directed 
transversely  at  the  summit,  becoming  progressively  more  oblique  towards 
the  lower  extremities  of  the  ambulacra  where  they  are  directed  upward  as 
they  approach  the  median  groove.  Interambulacral  areas  flat  or  very  slightly 
concave  in  a  transverse  direction;  deltoid  plates  small,  their  exposed  surfaces 
less  than  one-third  the  length  of  the  ambulacra,  their  dorsal  margins  straight 
and  meeting  at  the  median  line  in  an  angle  a  little  greater  than  90c. 

Remarks. — The  specimen  which  has  been  used  in  drawing  up  the  above 
description  is  from  the  Eenault  formation  at  Fairview,  Hardin  County,  from 
the  bed  which  Ulrich  has  called  zone  4  of  his  Ohara,  and  is,  therefore,  from 
exactly  the  same  stratigraphie  position  from  which  the  holotype  of  the  species 
is  recorded.  The  holotype  is  a  slightly  more  elongate  specimen  than  this 
one,  with  the  dorsal  region  relatively  a  little  shorter,  but  the  proportionate 
length  of  the  dorsal  region  of  this  specimen  is  less  than  in  the  second  example 
illustrated  by  Ulrich.  There  can  be  no  question  regarding  the  inclusion  of 
the  specimen  here  illustrated  in  the  same  species  with  the  holotype  of 
P.  buttsi,  though  it  is  perhaps  doubtful  whether  this  name  has  good  standing. 
Two  other  specimens  that  are  illustrated  here  are  from  the  Eenault  formation 
in  St.  Clair  and  Monroe  counties,  and  probably  would  not  be  identified  as 
P.  buttsi  by  Ulrich,  but  rather  as  P.  symmetricus  or  P.  ivelleri,  because  they 
occur  in  beds  that  are  assumed  by  him  to  be  considerably  younger  than  the 
"Upper   Ohara"   of    Hardin    County.      No   unprejudiced    observer,   however, 


324  GEOLOGY  OF  HARDIN  COUNTY 

could  fail  to  recognize  all  three  specimens  as  being  conspecific.  Still  other 
specimens  from  the  Kenault  formation  of  Union  County  are  illustrated,  which 
are  clearly  conspecific  with  those  from  Hardin  and  from  Monroe  and  St. 
Clair  counties. 

This  is  the  earliest  representative  of  the  elongate  type  of  pentremite  that 
has  been  referred  commonly  to  P.  pyriformis,  and  it  is  really  a  serious  ques- 
tion whether  that  name  should  not  be  retained  for  these  specimens.  Ulrich 
has  arbitrarily  restricted  the  name  P.  pyriformis  for  a  form  that  is  especially 
abundant  near  Huntsville,  Alabama,  and  has  at  the  same  time  proposed  no 
less  than  six  new  names  for  other  pyriform  species.  These  names  are  not 
accompanied  by  descriptions,  and  from  the  figures  alone  it  is  not  possible  to 
determine  just  how  the  specific  lines  have  been  drawn.  Certain  figures  are 
associated  under  one  specific  name  that  exhibit  less  resemblance  than  do  other 
figures  that  are  included  in  different  species.  The  original  description  of 
P.  pyriformis  by  Say,  was  not  accompanied  by  figures,  and  the  original 
definition  of  the  species  is  too  general  to  make  it  possible  to  determine  just 
what  form  is  referred  to,  if  the  specimens  are  to  be  differentiated  along  the 
lines  proposed  by  Ulrich. 

This  form  occurs  in  both  the  Renault  of  the  Mississippi  Valley  section, 
and  in  the  Renault  or  "Upper  Ohara"  of  the  Ohio  Valley,  and  in  both  places 
it  is  associated  with  P.  princetonensis,  or  P.  pinguis. 

Horizon  and  locality. — Renault  limestone,  Monroe,  St.  Clair,  Union,  and 
Hardin  counties,  Illinois. 

Pentremites  symmetricus  Hall 

Plate  IV,  Figs.  26-27 
1858.  Pentremites  symmetricus  Hall,  Geol.  Iowa,  vol.  1,  pt.  2,  p.  694,  pi.  25, 
fig.  12. 
Description. — Body  of  medium  size  or  smaller,  much  higher  than  wide, 
the  ventral  region  higher  than  the  dorsal,  the  greatest  width  at  the  extremities 
of  the  ambulacra.  The  dimensions  of  a  rather  small  but  very  complete 
specimen  are :  height  18.5  mm.,  greatest  width  12.8  mm,,  length  of  ambulacra 
12.6  mm.,  width  of  ambulacra  3.8  mm.,  distance  from  center  of  stem  facef 
to  base  of  ambulacra  9.5  mm.  Dorsal  region  obpyramidal,  with  the  faces  of 
the  pyramid  well  defined  towards  the  line  separating  the  dorsal  and  ventral 
regions,  and  gently  concave  transversely  between  the  lower  extremities  of 
the  ambulacra;  in  profile  the  sides  of  the  dorsal  region  are  nearly  straight  or 
very  slightly  curved  through  the  most  of  their  length,  commonly  becoming 
concave  for  a  short  distance  as  they  approach  the  margin  of  the  stem  facet. 
Ventral  region  with  the  sides  gently  convex  and  converging  to  the  truncate 
summit;  the  ambulacra  gently  convex  transversely  with  a  moderately  deep 
median  groove,  the  convexity  becoming  somewhat  greater  towards  the  lower 


PALEONTOLOGY  325 

extremities;  each  of  the  two  lateral  surfaces  gently  convex,  with  the  inner 
margins  sloping  rather  abruptly  to  the  median  groove;  longitudinally  the 
ambulacra  are  very  gently  convex  with  the  curvature  increasing  a  little 
towards  the  summit;  the  side  plates  from  six  to  nine  in  number  in  the  space 
of  3  mm.,  the  lateral  grooves  nearly  transverse  in  direction  towards  the 
summit,  becoming  quite  oblique  towards  the  distal  extremities.  The  inter- 
ambulacral  areas  gently  concave  transversely,  with  very  slightly  raised  lateral 
margins,  the  tips  of  the  deltoids  not  quite  reaching  to  the  summit.  The 
deltoid  plates  nearly  or  quite  one-half  the  length  of  the  ambulacra,  their 
dorsal  margins  straight  and  meeting  at  the  median  line  in  an  angle  greater 
than  a  right  angle. 

Remarks. — This  is  a  rather  common  form  in  the  Lower  Chester  faunas, 
and  may  be  recognized  by  its  slightly  concave  interambulacral  regions,  its 
dorsum  shorter  than  the  ventral  region,  and  by  its  somewhat  coarser  am- 
bulacral  side  plates  and  lateral  grooves  than  in  most  species.  In  all  pentre- 
mites  these  grooves  vary  in  coarseness  in  each  ambulacrum,  being  more  closely 
placed  towards  the  summit  than  in  the  distal  portions  of  the  ambulacra,  and 
the  numbers  given  in  the  descriptions  presented  here  are  the  numbers  that 
may  be  counted  in  a  unit  distance  of  3  mm.  near  the  summit  and  again  near 
the  distal  extremity  of  the  same  ambulacrum.  Observations  upon  many 
specimens  have  shown  that  the  size  of  these  plates  and  grooves  is  a  rather 
constant  character  in  the  various  species. 

Horizon  and  locality. — Renault  and  Paint  Creek  limestones,  St.  Clair, 
and  Monroe  counties,  Illinois. 

Pentremites  pykaaeidatus  Ulrich 

Plate  IV,  Figs.  21-24 
1905.  Pentremites  py  ram  id  at  us  Ulrich,  IT.  S.  Geol.  Surv.,  Prof.  Paper  Xo. 
36,  p.  61,  pi.  7,  figs.  12-14.  (Xame  and  illustration  published 
without  description.) 
Description. — Body  of  medium  size,  bipyramidal  in  form,  much  higher 
than  wide,  the  greatest  width  at  the  extremities  of  the  ambulacra.  The  di- 
mensions of  a  nearly  perfect  specimen  are:  height  20.8  mm.,  greatest  width 
15.1  mm.,  length  of  ambulacra  12.6  mm.,  greatest  width  of  ambulacra  4.5 
mm.  Dorsal  region  of  the  body,  below  the  ends  of  the  ambulacra,  sub- 
pyramidal  in  form,  the  faces  of  the  pyramid  not  sharply  defined  except 
towards  the  ambulacral  extremities  where  the  surfaces  are  nearly  flat  trans- 
versely, the  profile  of  the  dorsum  with  nearly  straight  sides,  the  basal  plates 
reaching  about  half  way  or  less  from  the  stem  facet  to  the  ends  of  the 
ambulacra.  Ventral  region  about  equal  to  or  somewhat  higher  than  the 
dorsal,  the  sides  converging  to  the  truncate  summit  with  a  very  gentle  convex 
curvature.      Surfaces   of  the   ambulacra   depressed  convex,   with   the  median 


326  GEOLOGY    OF    HARDIN    COUNTY 

groove  rather  strong.  Each  of  the  lateral  surfaces  unsymmetrically  depressed 
convex,  the  curvature  to  the  median  groove  more  abrupt  than  to  the  lateral 
margins,  side  plates  eight  to  ten  in  the  space  of  3  mm.,  the  lateral  grooves 
nearly  straight  and  transverse  towards  the  summit,  becoming  oblique  distally. 
The  interambulacral  regions  fiat  or  very  slightly  concave  in  a  transverse 
direction,  with  the  lateral  margins  very  slightly  elevated  towards  the  tips 
of  the  deltoid  plates.  The  deltoid  plates  rather  short,  their  tips  not  reaching 
to  the  summit. 

Remarks. — In  the  absence  of  any  definition  of  this  species  accompanying 
the  illustrations  to  which  the  name  was  originally  applied,  the  student  of 
these  forms  is  left  in  some  uncertainty.  Judging  from  specimens  in  the 
hands  of  the  writer,  however,  as  well  as  from  the  original  illustrations,  one  of 
the  more  essential  characters  seems  to  be  the  very  flat  interambulacral  regions 
ventrally,  this  flatness  continuing  across  the  dividing  line  for  some  distance 
into  the  dorsal  region.  Accompanying  this  character  are  the  short  deltoid 
plates,  and  the  very  gently  convex  ambulacra.  The  specimens  that  are  illus- 
trated herewith  are  all  from  the  Paint  Creek  formation,  two  from  Monroe 
County  and  two  from  Johnson  County.  The  larger  of  the  Johnson  County 
specimens  has  the  interambulacral  regions  a  little  less  flat  than  the  others, 
with  a  slight  tendency  to  a  concave  profile  of  the  dorsal  region,  in  these 
characters  approaching  the  forms  to  which  TJlrich  has  given  the  name  P. 
lyoni,  which  apparently  differs  from  P.  pyramidatus  chiefly  by  reason  of  its 
gently  concave  interambulacra.  None  of  the  specimens  here  illustrated  are 
as  large  as  the  original  specimens  figured  by  TJlrich,  but  this  difference  can 
scarcely  be  considered  as  justification  for  any  specific  separation. 

Horizon*  and  locality. — Paint  Creek  formation,  Monroe  and  Johnson 
counties,  Illinois. 

Pentremites  gemmiformis  Hambach 

Plate  X,   Figs.  9-10 
1884.     Pentremites  gemmiformis  Hambach,  Trans.  St.  Louis  Acad.  Sci.,  vol. 
4,  p.  553,  pi.  D,  fig.  5. 

This  species  is  characterized  by  the  elongate  dorsal  region  with  concave 
profile,  and  especially  by  the  broad  basal  truncation,  a  short  distance  above 
which  there  is  likely  to  be  a  slight  constriction,  giving  to  the  lower  portion  of 
the  body  a  slight  bulbous  appearance.  So  far  as  known  the  species  occurs 
only  in  the  Paint  Creek  horizon. 

Horizon  and  locality. — Paint  Creek  limestone,  St.  Clair  and  Randolph 
counties,  Illinois. 


PALEONTOLOGY  327 

Mesoblastus  glabek  (M.  &  W.) 

Plate  VIII,  Fig?.  25-28 
1869.     Granatocrinus  glaber  Meek  and  Worthen,  Proc.  Acad.  Nat.  Sci.  Phil., 

p.  91. 
1873.     Granatocrinus  glaber  Meek  and  Worth  en,  Geol.  Surv.  111.,  vol.  5,  p. 

537,  pi.  20,  fig.  11. 
1905.     Mesoblastus  glaber  ?  Ulrich,  Prof.  Paper,  U.  S.  Geol.  Surv.,  No.  36, 

p.  57,  pi.  6,  figs.  13-17. 
The  type  specimens  of  this  species  are  preserved  in  the  collections  of  the 
Illinois  State  Museum  of  Natural  History,  at  Springfield,  and  they  have 
been  made  available  to  the  writer  for  study  by  Dr.  A.  R.  Crook,  the  Director 
of  the  Museum.  These  specimens  are  from  Hardin  County,  Illinois,  and 
are  undoubtedly  examples  of  the  species  that  is  commonly  met  with  in  the 
Shetlerville  formation.  The  specific  name,  however,  is  a  misnomer.  The 
type  specimens  are  somewhat  worn  so  that  they  are  essentially  smooth,  but 
perfectly  preserved  specimens  are  distinctly  marked  by  rather  strong  lines  of 
growth  upon  the  deltoid  plates  and  upon  the  distal  portion  of  the  radial 
plates,  the  stronger  of  these  lines  being  parallel  with  the  suture  between  the 
deltoid  and  radial  plates. 

Horizon  and  locality. — Fredonia  limestone,  Cedar  Bluff,  near  Princeton, 
Kentucky;  Shetlerville  formation,  Hardin  County,  Illinois,  and  Crittenden 
County,  Kentucky;  Renault  formation,  Monroe  County.  Illinois. 

Dizygocbinus  peesculptus  Ulrich 

Plate  V,  Figs.  15-17 
1918.  Dizygocrinus  persculptus  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West. 
Ky.,  pi.  2,  figs.  24-26.  (Name  and  illustration  published  without 
description.) 
Description. — Calyx  of  medium  size,  unequally  biturbinate  in  form. 
The  dimensions  of  a  nearly  complete  body  are :  greatest  diameter  at  arm  bases 
19.3  mm.,  height  from  stem  facet  to  base  of  anal  tube  18.6  mm.,  height 
of  dorsal  cup  5.9  mm.  Dorsal  cup  depressed  subturbinate  in  form,  the  sides 
sloping  in  nearly  straight  lines  from  the  basal  disk  nearly  to  the  arm  bases 
where  there  is  a  slight  flaring  of  the  sides;  the  sutures  impressed,  the  plates 
convex  and  more  or  less  rugose,  those  of  the  radial  series  slightly  elevated 
medially  to  form  five  obscure  ridges  leading  from  the  radials  to  the  bases  of 
the  arms.  Basal  disc  rather  large,  the  stem  facet  occupying  about  one-half 
its  diameter;  radial  plates  wider  than  high,  followed  by  two  costals  in  each 
ray,  both  of  which  are  wider  than  high;  distichals  two  in  each  series.  Arm 
openings  four  from  each  ray,  making  twenty  in  all,  the  arms  unknown. 
Interbrachial  areas  occupied  by  one  large  plate  in  contact  with  the  radials, 
followed  by  two  or  three  smaller  plates  which  in  some  places,  at  least,  are 


328  GEOLOGY   OF   HARDIN    COUNTY 

slightly  joined  with  the  plates  of  the  tegmen.  Posterior  interradial  area 
with  an  anal  plate  somewhat  smaller  than  the  radial s,  this  followed  by  three 
smaller  plates  in  the  second  range,  and  these  again  by  two  or  three  still 
smaller  ones;  there  are  apparently  some  still  higher  plates  in  the  posterior 
interradial  area,  but  they  are  not  clearly  shown  in  the  specimens  under 
observation.  Tegmen  subcorneal,  considerably  higher  than  the  dorsal  cup,  the 
plates  small,  convex,  or  produced  into  low,  thorn-like  spines.  Anal  tube  not 
preserved. 

Remarks. — In  the  report  on  Mississippian  Formations  of  Western  Ken- 
tucky, where  Ulrich  names  and  illustrates  this  species  without  description,  it 
is  reported  as  coming  from  the  upper  part  of  the  "Ohara  limestone,"  two  and 
one-half  miles  north  of  Smithland,  Kentucky.  He  also  has  a  number  of 
specimens  in  his  collection,  either  of  this  species  or  I),  super  sies,,  from  near 
Levias,  Crittenden  County,  Kentucky,  which  are  labeled  as  coming  from  the 
"Upper  Ohara."  The  writer's  visit  to  the  Levias  locality  during  the  past 
season,  in  company  with  Mr.  Chas.  Butts,  showed  to  the  satisfaction  of  both, 
that  Ulrich  had  mistaken  and  mapped  the  Rosiclare  sandstone  at  this  locality 
for  the  "Cypress"  (Bethel),  and  that  consequently  the  "Upper  Ohara"  as  he 
has  identified  it,  is  really  Fredonia.  The  locality  north  of  Smithland  has 
not  been  reexamined,  but  it  seems  more  than  probable  that  some  similar 
mistake  was  made  in  the  horizon  at  that  locality. 

Most  diligent  search  during  four  years  field  work,  at  every  locality  that 
has  been  available,  has  brought  out  the  fact  that  every  specimen  of  Bato- 
crinoid  that  has  been  found  in  the  "Upper  Ohara,"  the  Shetlerville  and. 
Renault  formations  of  this  report,  and  so  far  as  known  they  occur  only  in 
the  Shetlerville,  is  a  member  of  the  species  Globo>crinus  unionensis.  On  the 
other  hand,  every  specimen  in  the  Ste.  Genevieve,  below  the  "Upper  Ohara,"  is 
is  a  Dizygocrinus,  members  of  which  genus  have  not  lost  the  first  costal  plates. 
Ulrich's  contention  that  these  crinoid  species  constitute  a  bond  of  union 
between  the  "Upper  Ohara"  and  the  remainder  of  his  Ste.  Genevieve  forma- 
tion, has  not  been  confirmed  by  these  recent  field  studies.  Ulrich's  collections 
were  made  a  score  or  more  years  ago,  at  a  time  when  the  stratigraphic  prob- 
lems involved  were  not  clearly  defined,  and  it  has  been  demonstrated  in  the 
Levias  locality  at  least,  that  an  error  was  made  in  stratigraphic  interpretation. 
Under  the  circumstances,  therefore,  none  of  the  evidence  which  he  has  pre- 
sented can  be  accepted  as  being  conclusive  until  it  has  been  confirmed  by 
new  observations. 

Dizygocrinus  persculptus  differs  from  D.  superstes  which  occurs  in  the 
same  horizon,  in  its  more  depressed  dorsal  cup,  and  in  the  more  rugose  nature 
of  the  surface  ornamentation  of  the  plates. 

Horizon  and  locality. — Fredonia  limestone,  Eosiclare,  Illinois,  and  Cedar 
Bluff  quarry,  near  Princeton,  Kentucky. 


PALEONTOLOGY  329 

Dizygocrinus  superstes  Ulrich 
Plate  V,  Figs.  13-14 
1918.     Dizygocrinus  superstes  Ulrich,  Ky.  Geol.   Surv.,  Miss.  Form.  West. 
Ky.,  pi.  2,  figs.  21-23.     (Name  and  illustration  published  without 
description.) 

Description. — Calyx  small  or  of  medium  size,  subequally  biturbinate ;  the 
dimensions  of  a  nearly  complete  body  are :  greatest  diameter  at  arm  bases 
10.7  mm.,  height  from  stem  facet  to  base  of  anal  tube  9.8  mm.,  height  of 
dorsal  cup  4.3  mm.  Dorsal  cup  subturbinate,  the  sides  sloping  in  nearly 
straight  lines  from  the  basal  disc  nearly  to  the  arm  bases  where  there  is  a 
slight  flaring  of  the  sides ;  the  sutures  impressed,  the  plates  convex  and  more 
or  less  nodose,  those  of  the  radial  series  slightly  elevated  medially  to  form 
five  obscure  ridges  leading  from  the  radial  plates  to  the  bases  of  the  arms. 
Basal  disc  small,  the  stem  facet  occupying  about  half  its  diameter;  radial 
plates  wider  than  high,  followed  by  two  costals  in  each  ray,  both  of  which  are 
wider  than  high;  distichals  two  in  each  series,  except  in  the  anterior  ray 
where  there  are  three.  Arm  openings  two  in  the  anterior  ray,  those  of  the 
postero-lateral  rays  not  clearly  exhibited  but  on  one  side  there  seems  to  be 
four  openings,  on  the  other  not  so  many;  four  is  probably  the  normal  num- 
ber, making  eighteen  in  all.  The  arms  unknown.  Interbrachial  areas  occu- 
pied by  one  large  plate  in  contact  with  the  radials,  followed  by  three  or  four 
smaller  plates  arranged  in  two  or  three  series.  Posterior  inter-radial  area 
with  an  anal  plate  somewhat  smaller  than  the  radials,  this  followed  by  three 
smaller  plates  in  the  second  range  and  these  again  by  three  still  smaller  ones; 
there  are  apparently  some  still  higher  plates  but  they  are  not  clearly  exhibited 
in  the  specimens  observed.  Tegmen  subcorneal,  about  as  high  as  or  a  little 
higher  than  the  dorsal  cup,  the  plates  small,  convex,  or  produced  into  rather 
prominent,  central  tubercles.     Anal  tube  not  preserved. 

Remarks. — The  specimens  of  Dizygocrinus  that  have  been  met  with  in 
the  Ste.  Genevieve  limestone  seem  to  represent  two  species.  In  the  absence 
of  any  descriptions  by  Ulrich,  these  two  species  seem  to  correspond  with  those 
to  which  he  has  given  the  names  D.  superstes  and  D.  persculptus.  The  two 
species  differ  in  the  relative  height  of  the  dorsal  cup,  in  the  ornamentation  of 
the  plates,  and  in  the  number  of  arm  openings.  In  D.  superstes,  the  species 
here  described,  the  dorsal  cup  is  relatively  higher  than  in  D.  persculptus,  it 
being  nearly  or  quite  as  high  as  the  tegmen  to  the  base  of  the  anal  tube ;  the 
plates  too  are  more  smoothly  nodose,  their  surface  not  being  so  broken  up  with 
rugosities.  In  the  best  specimen  available  for  study  there  are  only  two  arm 
openings  in  the  anterior  ray  in  D.  superstes,  while  in  D.  persculptus  there 
are  four  openings  in  each  ray.  It  is  impossible  to  determine  from  Ul rich's 
illustration,  in  the  absence  of  any  description,  the  number  of  arm  openings 
in  the  anterior  ray  of  the  holotype,  and  it  is  therefore  possible  that  the  two 
openings  observed  may  be  an  abnormal  character. 


330  GEOLOGY    OF    HARDIN    COUNTY 

When  Worthen  described  Batocrinus  unionensis  he  illustrated  two  speci- 
mens, which  quite  evidently  are  different  species  and  are  here  considered  as 
representing  different  genera.  The  specimen  without  arms,  which  quite  cer- 
tainly was  the  one  used  for  the  most  part  in  the  preparation  of  the  specific 
definition,  has  here  been  accepted  as  the  holotype  and  has  been  placed  in  the 
new  genus  Globocrinus.  The  second  specimen,  the  one  with  the  arms,  differs 
from  the  first  in  having  the  two  costal  plates  in  each  ray  which  are  normal 
for  the  genus  Dizygocrinus  and  its  close  allies.  This  second  specimen  is 
clearly  a  close  relative  of  the  two  species  of  Dizygocrinus  that  are  here 
described  from  the  Fredonia  limestone,  and  judging  from  the  illustration  it 
is  more  nearly  related  to  I),  sup  erst  es,  and  is  not  unlikely  a  member  of  this 
species.  Worthen^s  specimens  are  said  to  come  from  the  "St.  Louis  division 
of  the  Lower  Carboniferous,  Union  County,  Illinois,'7  but  at  that  time  lie 
included  all  the  strata  below  the  first  massive  sandstone  formation  of  the 
section,  which  was  believed  to  be  the  basal  member  of  the  Chester  group,  in 
the  St.  Louis  limestone.  This  first  massive  sandstone  in  Union  County  is  the 
Cypress,  so  Worthen's  so-called  St.  Louis  would  include  both  the  Ste. 
Genevieve  and  also  the  lower  Chester  formations.  In  the  neighborhood  of 
Anna,  in  Union  County,  there  are  exposures  of  both  the  Fredonia  limestone 
and  of  the  Shetlerville  and  Renault  formations,  and  Worthen's  two  speci- 
mens were  doubtless  collected  from  these  two  formations, — at  least  all  field 
experience  farther  east  would  lead  to  such  a  supposition, — but  both  of  the 
species  must  be  collected  again  in  order  to  confirm  their  exact  stratigraphic 
positions. 

Horizon  and  locality. — Fredonia  limestone,  Charles  Stone  Quarry,  near 
Joppa  Junction,  Johnson  County,  Illinois,  and  Eosiclare,  Illinois. 

GLOBOCRINUS  n.  gen. 

This  genus  is  a  member  of  the  family  Batocrinidae,,  and  although  its 
arms  have  not  been  observed  it  seems  to  be  related  to  Dizygocrinus.  The 
essential  generic  character  is  found  in  the  reduction  of  the  costals  to  a  single 
plate  in  each  ray,  there  being  no  small,  quadrangular  plate  lying  between 
the  axillary  costal  and  the  radial,  as  in  Dizygocrinus,  or  in  fact,  in  all  closely 
related  members  of  the  family.  In  the  original  specimen  of  the  genotype 
there  are  only  two  plates  following  the  anal  in  the  posterior  interambulacral 
space,  this  arrangement  of  plates  being  a  characteristic  of  the  family  Actino- 
crinidae,  but  all  other  specimens  examined  possess  the  three  plates  that  are 
normally  present  in  the  Batocrinidae.  The  loss  of  the  middle  one  of  these 
three  plates  is  not  an  unusual  abnormal  character  among  the  Batocrinidae, 
and  this  is  undoubtedly  the  explanation  of  the  condition  in  the  type  of 
G.  unionensis. 

A  loss  or  reduction  in  number  of  plates  among  the  camerate  crinoids  is 
well  recognized  as  a  progressive  character,  and  the  fact  that  we  have  in  this 


PALEONTOLOGY  331 

species  a  batocrinid  in  which  the  costal s  have  been  reduced  in  number  to  a 
single  plate  in  each  ray,  would  suggest  to  any  student  of  crinoids,  even  if  he 
did  not  know  the  horizon  from  which  the  species  was  collected,  that  it  occurred 
late  in  the  history  of  the  family.  It  is  in  fact,  the  last  known  representative 
of  the  family,  and  the  reduced  number  of  brachial  plates  is  just  the  sort  of 
character  that  would  be  looked  for  here.  The  loss  of  these  costal  plates  is 
such  an  unusual  character  that  it  is  certainly  worthy  of  recognition  as  of 
generic  value.  The  name  Globocrinus  is  given  to  the  genus  because  of  the 
subglobular  form  of  the  body. 

Globocrinus  unionensis   (Worthen) 

Plate  V,  Figs.  18-23 
1890.     Batocrinus  unionensis  Worthen,  Geol.  Surv.  111.,  vol.  8,  p.  84,  pi.  12, 

figs.  5-5a,   (not  pi.  13,  fig.  3).      (Xot  D'izygocrinus  unionensis  W. 

and  Sp.,  1897.) 
Description. — Calyx  small  or  of  moderate  size,  subglobular  or  depressed 
subglobular  in  form,  the  dimensions  of  the  holotype  being:  greatest  diameter 
at  arm  bases  20  mm.,  height  from  stem  facet  to  base  of  anal  tube  16  mm., 
height  of  dorsal  cup  8.5  mm.  The  dimensions  of  a  second  nearly  perfect 
calyx  are:  greatest  diameter  at  arm  bases  16  mm.,  height  from  stem  facet  to 
base  of  anal  tube  15  mm.,  height  of  dorsal  cup  8  mm.  Dorsal  cup  bowl- 
shaped,  the  sides  convexly  curved  from  the  stem  facet  to  the  bases  of  the 
arms,  the  sutures  impressed,  surfaces  of  the  plates  convex,  commonly  flattened 
on  top,  either  nearly  smooth  or  ornamented  by  low,  irregularly  reticulating 
ridges.  Basal  disc  small,  the  stem  facet  concave,  occupying  half  or  more  than 
half  of  the  diameter  of  the  base;  radials  wider  than  high;  one  costal  only  in 
each  ray,  wider  than  high;  the  higher  brachials  in  the  cup  commonly  wider 
than  high,  two  disti dials  in  each  division  of  the  rays  except  in  the  anterior 
ray ;  interbrachial  plates  one  or  two  in  each  interradial  area  except  posteriorly ; 
in  the  posterior  interradius  the  anal  plate  normally  followed  by  three  plates, 
but  abnormally  in  the  holotype  by  only  two  plates;  these  in  turn  followed 
by  a  single  plate  which  does  not  connect  with  the  tegmen.  When  normally 
developed  there  are  four  arm-openings  from  each  ray,  except  the  anterior  one 
which  has  only  two,  making  eighteen  in  all;  the  arms  themselves  unknown. 
Tegmen  subcorneal  from  the  arm  bases  to  the  base  of  the  anal  tube,  the 
plates  small,  convex,  a  part  or  all  of  them,  especially  the  larger  ones,  sur- 
mounted by  low  spines  or  thorn-like  extensions;  anal  tube  apparently  strong, 
its  length  unknown. 

Remarks. — This  species  was  originally  described  by  Worthen  as  Bato- 
crinus unionensis,  and  was  said  to  come  from  "St.  Louis  division  of  the 
Lower  Carboniferous,  Union  County,  Illinois/'  Two  specimens  were  illus- 
trated by  him,  one  lacking  the  arms   (pi.  12,  figs.  5-5a)   and  the  other  with 


332  GEOLOGY    OF    HARDIN    COUNTY 

the  arms  in  position  (pi.  13,  fig.  13).  The  definition  was  for  the  most  part 
drawn  up  from  the  specimen  without  arms,  this  specimen,  furthermore,  being 
the  one  illustrated  upon  an  earlier  plate  in  the  report  containing  the  descrip- 
tion, and  it  may  properly  be  selected  as  the  holotype  of  the  species.  This 
holotype  is  now  preserved  in  the  collection  of  the  Illinois  State  Museum  at 
Springfield,  and  the  writer  is  indebted  to  Dr.  A.  E..  Crook,  curator  of  that 
institution,  for  the  opportunity  to  study  the  specimen.  The  second  specimen, 
with  arms,  has  not  been  seen  by  the  writer,  it  is  not  listed  in  the  collections 
of  the  State  Museum,  and  if  it  is  still  in  existence  its  whereabouts  is  unknown. 
It  is  certainly  specifically  distinct  from  the  selected  holotype,  and  doubtless 
was  collected  from  a  different  geological  horizon.  It  is  quite  certain  that 
neither  specimen  came  from  the  St.  Louis  limestone. 

Worthen's  definition  of  the  species  is  misleading.  The  holotype  is 
peculiar,  among  the  related  batocrinid  forms,  in  possessing  a  single  costal 
plate  in  each  ray,  the  usual,  small,  quadrangular  costal  lying  between  the 
radials  and  the  axillary  costals  being  missing.  It  is  this  feature  doubtless, 
which  led  Worthen  to  misinterpret  the  specimen.  In  order  to  provide  for  the 
two  costals  which  are  commonly  present  in  these  batocrinid  forms  he  inter- 
preted the  radials  as  first  costals,  below  these  he  described  the  radials  "as 
projecting  so  as  to  form  a  prominent  rim  around  the  basal  cavity."  The 
basals  he  described  as  being  "very  small  and  concealed  in  the  basal  cup." 
Examination  of  the  specimen  shows  that  the  basals  and  "first  radials"  to- 
gether, as  described  by  Worthen,  constitute  the  basal  disc  of  the  specimen ;  it 
is  divided  by  three  sutures  into  three  equal  basal  plates  and  does  not  differ 
in  any  essential  feature  from  the  base  of  other  batocrinids.  The  one  essential 
feature  in  which  the  specimen  does  differ  from  all  other  batocrinids  is  in  the 
loss  of  the  first  costal  plates.  This  plate  occasionally  is  lost  abnormally  in 
a  single  ray  in  certain  individuals  of  Dizygocrinus  and  perhaps  in  other 
genera,  but  in  G.  unionensis  these  plates  are  all  consistently  wanting  in  all 
specimens,  and  it  is  not  alone  a  good  specific  character,  but  may  be  counted 
as  of  generic  value. 

This  species,  differing  in  no  essential  features  from  the  type,  has  been 
collected  at  various  localities  in  Hardin  County,  Illinois,  and  in  Crittenden 
County,  Kentucky,  where  it  is  a  very  characteristic  species  in  the  fauna  of 
the  Shetlerville  formation,  the  very  basal  member  of  the  Chester  group  in 
that  region.  This  horizon  is  known  to  be  present  in  Union  County,  along 
Swan  Creek  near  Anna,  and  it  is  safe  to  assume  that  Worthen's  specimen 
was  secured  from  this  same  horizon  as  that  which  has  afforded  the  specimens 
from  Hardin  and  Crittenden  counties. 

In  the  figure  of  Worthen's  second  specimen,  the  one  with  the  arms,  the 
presence  of  small,  quadrangular,  first  costal  plates  is  clearly  shown.  It  also 
differs  from  the  holotype  in  having  the  sides  of  the  dorsal  cup  nearly  straight 
between  the  arm  bases  and  the  top  of  the  column,  instead  of  distinctly  con- 


PALEONTOLOGY  333 

vex,  as  in  the  case  of  the  true  G.  unionensis.  This  specimen  is,  in  fact, 
essentially  like  a  form  rather  commonly  met  with  in  the  Ste.  Genevieve  lime- 
stone at  many  localities,  which  has  been  named  Dizygocrinus  superstes  by 
Ulrich.  The  Ste.  Genevieve  limestone  is  well  exposed  in  Union  County,  and 
Worthen's  arm-bearing  specimen  doubtless  came  from  that  formation,  but 
Worthen  did  not  recognize  the  Ste.  Genevieve  limestone  as  a  distinct  forma- 
tion, and  both  the  Shetlerville  and  Ste.  Genevieve  formations  in  Union  County 
lie  below  the  lowest  massive  sandstone  formation  of  the  Chester  group,  the 
base  of  which  Worthen  apparently  assumed  to  be  the  upper  limit  of  the  "St. 
Louis  division  of  the  Lower  Carboniferous.*' 

It  is  quite  clear  that  none  of  the  specimens  illustrated  as  Dizygocrinus 
unionensis  by  Wachsmuth  and  Springer  in  their  "North  American  Crinoidea 
Camerata"  is  truly  a  member  of  this  species,  and  all  of  them  are  much  more 
closely  allied  to  the  arm-bearing  specimen  illustrated  by  Worthen  than  to  the 
holotype  of  G.  unionensis. 

Horizon  and  locality. — Shetlerville  formation,  Union  and  Hardin  coun- 
ties, Illinois;  Crittenden  County,  Kentucky. 

Platycrinus  penicillus  (Meek  and  Worthen) 

Plate  V,  Figs.  1-4 
.     Platycrinus  Huntsvillae  Troost,  unpublished  manuscript. 


1860.     Platycrinus  penicillus  Meek  and  Worthen,  Proc.  Acad.  Nat.  Sci.  Phil., 

p.  380. 
1866.     Platycrinus  penicillus  Meek  and  Wxorthen,  Geol.  Surv.  111.,  vol.  2,  p. 

266,  pi.  19,  figs.  6a-c. 
1897.     Platycrinus  Huntsvillae  Wachsmuth  and   Springer,   N.   Amer.   Crin. 

Cam.,  p.  678,  pi.  73,  figs.  6,  7a-b,  8-12. 
1905.     Platycrinus  huntsvillae  Ulrich,  Prof.  Paper,  U.  S.  Geol.  Surv.  No.  36, 

p.  58,  pi.  6,  figs.  27a-i. 
One  of  the  commonest  and  most  characteristic  members  of  the  Ste. 
Genevieve  limestone  fauna  in  both  the  Mississippi  and  Ohio  valleys,  is  a 
crinoid  which  has  been  referred  commonly  to  Platycrinus  huntsvillae.  The 
column  joints  of  this  crinoid  are  the  parts  most  commonly  met  with.  They 
are  characterized  by  their  elliptical  outline  and  by  a  row  of  short  spines 
which  project  radially  from  the  margin  like  the  handles  of  a  ship's  steering 
wheel.  The  basal  plates  of  the  calyx  are  characterized  by  the  presence  of 
three  radiating  ridges  which  coincide  with  the  three  anchylosed  sutures  of 
the  base. 

The  manuscript  name  P.  huntsvillae  was  given  to  this  crinoid  by  Troost 
as  early  as  1850,  but  neither  description  nor  illustration  of  the  species  was 
published  at  that  time.  In  1860  Meek  and  Worthen  defined  the  species  from 
Hardin  County,  Illinois,  under  the  name  P.  penicillus,  and  later,  in  1866, 


33-4  GEOLOGY  OF  HARDIN  COUNTY 

they  republished  their  definition  with  illustrations.  The  name  P.  huntsvillae 
was  never  actually  used  in  connection  with  a  description  of  the  species  until 
1897,  when  it  was  revived  by  Wachsmuth  and  Springer  in  their  monograph 
of  North  American  camerate  crinoids.  According  to  this  the  first  actually 
published  name  for  the  species  was  P.  penicillus,  given  by  Meek  and  Worthen, 
and  this  name  should  be  given  preference  over  Troost's  unpublished  manu- 
script name  which  has  been  in  common  use  since  the  appearance  of  Wachs- 
muth and  Springer's  monograph. 

A  little  careful  search  will  almost  invariably  bring  to  light  specimens 
of  this  species  in  any  Fredonia  outcrop,  and  they  can  be  found  in  the  "Lower 
Ohara"  also  in  most  localities;  but  the  most  diligent  search  on  every  possible 
occasion  has  utterly  failed  to  establish  the  presence  of  the  species  in  any 
exposure  of  the  "Upper  Ohara"  strata.  On  the  other  hand  the  species  does 
occur  in  undisputed  St.  Louis  limestone,  and  in  some  of  the  ravines  west  of 
Cave  in  Eock,  will  preserved  bases  have  been  observed  in  beds  which  are 
well  beneath  strata  carrying  the  characteristic  Lithostrotion  canadensis  of 
the  St.  Louis.  This  species,  therefore,  constitutes  a  distinct  bond  between 
the  Ste.  Genevieve  limestone  and  the  St.  Louis,  but  the  genus  becomes  entirely 
extinct,  so  far  as  we  now  know,  before  the  beginning  of  the  Lower  Chester 
"Upper  Ohara"  beds. 

Horizon  and  locality. — St.  Louis  limestone,  Hardin  County,  Illinois. 
Ste.  Genevieve  limestone,  wherever  the  formation  is  exposed. 

DlCHOCRINUS   GIRTYI  n.   sp. 

Plate  V,  Figs.  5-12 
Description. — Calyx  subovate  or  slightly  subpyriform,  the  maximum 
diameter  about  three-fourths  of  the  total  height.  The  dimensions  of  a  nearly 
complete  calyx  are :  greatest  diameter  at  arm  bases  8  mm.,  height  from  stem 
facet  to  summit  of  tegmen  10.2  mm.,  height  of  dorsal  cup  7  mm.  Dorsal 
cup  obconical,  slightly  constricted  just  above  the  stem  facet  which  is  sur- 
rounded by  a  flange-like  extension,  the  sides  gently  convex  from  just  above  the. 
constriction  to  the  arm  bases.  The  basal  cup  with  two  plates  which  extend 
about  one-third  the  distance  from  the  stem  facet  to  the  arm  bases.  Radial 
plates  subquadrangular  in  outline,  higher  than  wide,  the  postero-lateral  ones 
somewhat  narrower  than  the  other  three.  The  anal  plate  nearly  or  quite  as 
large  as  the  radials,  but  a  little  shorter.  Surface  of  the  plates  of  the  dorsal 
cup  ornamented  with  more  or  less  discontinuous  and  somewhat  wavy  ridges, 
on  the  radial  plates  the  longer  of  these  ridges  radiating  from  the  arm  bases  to 
the  lower  angles  of  the  plates,  the  intervening  spaces  being  occupied  by 
shorter  ridges  lying  in  a  general  direction  parallel  with  the  plate  margins; 
on  the  basal  plates  "the  more  continuous  ridges  extend  from  the  lower  angles 
of  the  radial  plates  to  the  flange  surrounding  the  stem  facet;  between  these 


PALEONTOLOGY  335 

longer  ridges  the  others  extend  horizontally.  Costal  plates,  pentagonal  in 
outline,  apparently  one  in  each  ray,  very  small,  their  width  being  about  one- 
fifth  or  one-sixth  of  the  width  of  the  radial s,  and  their  length  about  equaling 
their  width;  these  small  plates  may  be  constituted  of  two  closely  united,  but 
this  is  not  evident  in  the  specimens  studied.  The  costal  plates  are  followed 
by  at  least  two  small  distichals  in  each  series,  the  succeeding  plates  being 
wanting  in  the  specimens  examined.  The  tegmen  is  gently  convex  on  top 
curving  downward  abruptly  on  the  sides  between  the  arm  bases,  rather  dis- 
tinctly separated  from  the  plates  of  the  dorsal  cup  by  shallow,  horizontal 
constrictions  or  furrows  between  the  arm  bases,  this  constriction  being  more 
profound  upon  the  posterior  side;  in  the  depressed  interambulacral  portions 
of  the  tegmen,  three  or  four  larger  plates ;  the  posterior  interambulacral  area 
broader  than  the  others  with  a  larger  number  of  plates,  the  anal  opening 
small  and  circular,  directed  laterally  and  situated  a  little  above  the  junction 
of  the  tegmen  with  the  dorsal  cup;  the  ambulacral  plates  of  the  tegmen 
smaller  than  the  interambulacrals ;  five  somewhat  larger  interradial  plates 
in  the  central  portion  of  the  tegmen  being  probably  the  orals,  the  posterior 
one  being  crowded  between  the  others.  The  orals  and  some  of  the  surround- 
ing plates,  especially  in  the  ambulacral  directions  are  distinctly  tuberculate, 
the  tubercles  growing  smaller  distally ;  the  plates  of  the  depressed  inter- 
ambulacral areas  are  essentially  smooth. 

Remarks. — This  species  has  been  established  upon  a  very  perfect  calyx 
preserving  both  the  dorsal  cup  and  the  tegmen,  and  a  second  somewhat  larger, 
nearly  perfect  dorsal  cup,  both  from  the  Shetlerville  formation  in  Hardin 
County.  These  two  examples  are  the  cotypes  of  the  species.  Aside  from 
these  specimens  a  number  of  fragments,  separate  radial  plates  especially,  have 
been  met  with.  The  most  notable  of  these  fragmentary  examples  are  from 
the  Paint  Creek  formation  in  St.  Clair  Country,  Illinois,  where  two  examples 
have  been  collected,  both  from  the  same  locality.  One  of  these  specimens  is 
a  practically  complete  base  which  is  entirely  like  those  collected  in  Hardin 
County  except  that  it  is  about  twice  as  large.  The  second  example  is  a  crushed 
calyx  exhibiting  two  of  the  radials  nearly  complete  and  a  fragment  of  the  base. 
Like  the  base  with  which  it  is  associated  this  crushed  specimen  is  considerably 
larger  than  the  Hardin  County  examples,  and  the  surface  markings  are  some- 
what more  regular  in  their  arrangement  than  in  either  of  the  cotypes.  The 
difference  in  the  character  of  the  surface  markings,  however,  is  scarcely 
greater  than  that  observed  among  the  examples  collected  from  one  locality  in 
Hardin  County,  and  there  is  certainly  not  enough  difference  between  the 
Hardin  and  St.  Clair  County  examples  to  warrant  separating  them  speci- 
fically. 

The  species  is  quite  distinct  in  form  and  ornamentation  from  any  of  the 
older  members  of  the  genus.  It  is  not  evident  that  it  possesses  the  two  small 
costal  plates  that  are  said  by  Wachsmuth  and  Springer  to  characterize  the 


336  GEOLOGY   OF    HARDIN    COUNTY 

genus;  there  appears  to  be  only  a  single  plate  in  each  costal  series,  although 
it  is  possible  that  two  very  small  plates  may  be  closely  united. 

Horizon  and  locality. — Shetlerville  formation,  Fairview  bluff  below  Rosi- 
clare,  and  east  of  Shetlerville,  Illinois;  Paint  Creek  formation,  Prairie  du 
Long  Creek,  northwest  of  Floraville,  St.  Clair  County,  Illinois. 

Genus  TALAROCRINUS 

The  genus  Talarocrinus  is  an  important  one  in  the  interpretation  of  the 
Lower  Chester  faunas.  In  their  monograph  on  the  camerate  crinoids,  Wachs- 
muth  and  Springer1  state  that  the  genus  is  "probably  restricted  to  the  age  of 
the  Warsaw  and  St.  Louis  groups,"  but  it  is  now  determined  that  all  of  the 
known  species  of  the  genus,  except  T.  simplex  which  is  from  the  Spergen 
limestone,  occur  in  the  Lower  Chester  formations  and  nowhere  else.  T.  sim- 
plex is  quite  different  from  the  other  members  of  the  genus,  and  since  the 
characters  of  its  arms  and  tegmen  are  entirely  unknown,  it  is  not  improbable 
that  it  may  belong  to  a  genus  distinct  from  the  true  Talarocrinus  whose 
genotype  is  T.  cornigerus.  As  known  now  the  genus  occurs  in  the  Renault 
and  Paint  Creek  formations  in  the  Mississippi  Valley,  in  the  "Upper  Ohara" 
limestone  of  Hardin  County,  Illinois,  and  the  adjacent  part  of  Kentucky,  and 
in  the  two  divisions  of  the  "Gasper"  limestone  elsewhere  in  Kentucky.  No 
member  of  the  genus  is  recorded  from  the  Fredonia  limestone  or  the  "Lower 
Ohara"  limestone.  All  of  the  evidence  afforded  by  the  members  of  the  genus 
goes  to  show  that  the  Talarocrinus  zone  is  a  contemporaneous  horizon  from 
St.  Clair  County,  Illinois,  to  central  Kentucky,  although  Ulrich  would  ex- 
clude the  Talarocrinus-hearmg  beds  of  Hardin  County  from  this  horizon  and 
place  them  lower  in  the  stratigraphic  column.  His  reason  for  doing  this,  so 
far  as  Talarocrinus  is  concerned,  is  that  in  the  application  of  his  method  of 
correlation  by  matching  individuals,  he  has  not  found  a  specimen  from  the 
"Upper  Ohara"  limestone  that  according  to  his  standards  exactly  matches 
any  specimen  he  has  seen  from  the  typical  Eenault,  and  therefore  he  con- 
cludes that  these  two  formations  are  not  contemporaneous  and  he  assigns 
the  "Upper  Ohara"  to  a  position  lower  in  the  stratigraphic  column  than 
the  Eenault.  The  species  commonly  met  with  in  the  "Upper  Ohara"  is 
T.  trijugis,  although  T.  inflatus  is  certainly  present,  and  out  of  the  thousands 
of  fragmentary  individuals  that  have  been  observed,  scarcely  half  a  dozen 
preserve  the  characters  of  the  tegmen  which  are  essential  for  certain  specific 
determination.  In  the  typical  Renault  the  species  commonly  met  with  is 
T.  inflatus,  which  also  is  commonly  preserved  in  such  a  condition  that  its 
essential  specific  characters  are  not  exhibited.  The  characters  of  the  dorsal 
cups  of  the  two  species  are  the  same,  and  from  the  dorsal  cup  alone  it  is  not 
possible  to  separate  the  two  species,  nor  can  either  of  them  be  distinguished 

XN.  Amer.  Crin.   Cam.,  vol.   2,  p.   782,    (1897). 


PALEONTOLOGY  337 

from  T.  cornigerus.  The  differences  between  these  three  species  are  found  in 
the  relative  development  of  spines  upon  the  ambulacral  plates  of  the  tegmen. 
In  T.  inflatus  no  spines  are  present,  in  T.  cornigerus  the  most  prominent 
spines  are  developed,  and  T.  trijugis  occupies  an  intermediate  position.  If 
all  the  fragmentary  specimens  that  are  met  with  were  complete,  it  is  not  un- 
likely that  all  three  species  would  be  found  throughout  these  Talarocrinus- 
bearing  beds,  but  as  we  know  them  from  present  collections  of  complete 
bodies,  we  know  that  T.  inflatus  and  T,  cornigerus  are  both  present  in  the 
typical  Renault  of  Randolph  County,  and  T.  inflatus  and  T.  trijugis  are 
found  together  in  the  Renault  beds  of  Union  County.  No  well  defined 
examples  of  T.  cornigerus  have  been  observed  in  the  "Upper  Ohara,"  although 
T.  inflatus  is  present,  but  the  associations  of  the  species  in  Randolph,  Union, 
and  Hardin  counties  show  that  all  three  lived  contemporaneously,  and  that  in 
all  probability  they  are  nothing  more  than  geographic  variations  of  a  single 
form. 

Neither  in  the  Mississippi  Valley  nor  in  the  Ohio  Valley  during  a  most 
diligent  search  for  four  years,  has  a  single  example  of  Talarocrinus  been  met 
with  in  any  true  Ste.  Genevieve  limestone,  nor  has  a  single  example  of 
Platijcrinus  penicillus  been  found  above  the  top  of  the  true  Ste.  Genevieve. 
Furthermore,  the  associates  of  Talarocrinus  in  the  "Upper  Ohara"  are  every 
one  found  in  the  typical  Renault  or  the  Paint  Creek.  These  two  faunal  zones 
are  everywhere  distinct  throughout  the  region  studied,  and  every  bit  of  evi- 
dence, both  stratigraphic  and  faunal  goes  to  show  that  each  of  these  two 
zones  is  a  contemporaneous  horizon  from  St.  Clair  County,  Illinois,  to 
central  Kentucky. 

Talarocrinus  inflatus  Ulrich 

Plate  VI,  Figs.  1-13 
1918.     Talarocrinus  inflatus  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West.  Ky., 
pi.  8,  figs.   14-15,  pi.  9,  figs.  4-6.      (Xame  and  illustrations  pub- 
lished without  description.) 
Description. — Body,  when  complete  without  the  arms,  subellipsoidal  or 
subspherical  in  form,  usually  higher  than  wide,  but  an  occasional  specimen 
has  the  height  and  width  nearly  equal.     The  dimensions  of  a  nearly  perfect 
body  are:  height   18  mm.,  greatest  width   15.8  mm.,  height  of  dorsal  cup 
10.2  mm.,  greatest  width  of  base   10.8  mm.     Dorsal  cup  bowl-shaped,  the 
surface  of  the  plates  smooth,  their  contour  rather  strongly  convex  in  mature 
specimens,  with  the  sutures  impressed,  the  base  distinctly  bilobed  by  reason 
of  the  impressed  suture  separating  the  two  plates.    The  radial  plates  diverging 
more  or  less  from  the  base  to  the  top  of  the  dorsal  cup,  the  anal  plate  similar 
in  form  and  size  to  the  radials.     Tegmen  not  so  high  as  the  dorsal  cup,  its 
center   occupied   by   a   large   plate  whose   whole   surface   is   elevated   into   a 
—22  G 


338  GEOLOGY    OF    HARDIN    COUNTY 

prominent  node  that  is  somewhat  flattened  antero-posteriorly ;  from  the 
central  nodose  plate  the  ambnlacral  regions  radiate  as  rounded  shoulders,  each 
including  ten  or  more  small  plates  with  depressed  convex  surfaces;  the  inter- 
ambulacral  regions  depressed  and  four  of  them  appearing  as  rather  narrowly 
rounded  furrows  which  curve  downward  to  the  margins  of  the  dorsal  cup; 
the  posterior  interradial  area  broader  than  the  others,  the  anal  opening  situated 
upon  a  prominence  made  up  of  many  small  plates,  which  extends  well  up 
towards  the  large  central  plate  of  the  tegmen,  the  opening  directed  laterally 
or  obliquely  upwards.  The  arms  in  two  pairs  from  each  ray,  making  twenty 
altogether;  they  are  uniserial  near  the  base,  but  above  the  first  five  or  six 
plates  they  become  biserial ;  their  length  is  commonly  a  little  more  than  twice 
the  height  of  the  dorsal  cup. 

Remarks. — This  species  is  the  common  member  of  the  genus  in  the 
typical  Renault  limestone  of  Monroe  and  Randolph  counties,  but  it  also 
occurs  in  Hardin  County.  The  specimen  from  which  the  above  description 
has  been  chiefly  drawn  up  is  probably  from  the  same  locality  as  Ulrich's 
holotype  of  the  species,  and  in  some  respects  it  is  a  better  representative  of 
the  species  than  the  one  illustrated  by  Ulrich.  The  species  exhibits  a  con- 
siderable degree  of  variation  in  the  proportional  height  of  the  dorsal  cup 
and  in  the  convexity  of  the  plates  of  the  cup.  The  convexity  evidently  in- 
creases with  the  age  of  the  individual,  as  is  shown  in  a  series  of  specimens 
from  the  type  locality.  The  characteristic  features  of  the  species  seem  to  be 
in  the  nature  of  the  plates  of  the  tegmen,  especially  in  the  large  central  plate 
with  its  flattened  node,  and  the  small  plates  of  the  ambulacral  regions  which 
are  not  produced  into  tubercles  or  spines. 

Horizon  and  locality. — Renault  limestone,  St.  Clair,  Monroe,  Randolph, 
Union,  and  Hardin  counties,  Illinois;  also  Ste.  Genevieve  County,  Missouri. 

Talarocrinus  trijugis  Miller  and  G-urley 

Plate  VI,  Figs.  17-26 
1894.     Talarocrinus  trijugis  M.  &  G.,  Bull.  111.  State  Mus.  Nat.  Hist.,  No. 

3,  p.  45,  pi.  3,  figs.  9-11. 
1918  Talarocrinus  trijugis  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West.  Ky., 
pi.  8,  figs.  11-13,  pi.  9,  figs.  10-11. 
Description. — Body,  when  complete  without  the  arms,  subellipsoidal  in 
form,  higher  than  wide.  The  dimensions  of  the  holotype  are :  height  14  mm., 
greatest  width  13  mm.,  height  of  dorsal  cup  6.5  mm.,  greatest  width  of  the 
base  8  mm.  Dorsal  cup  bowl-shaped,  the  surface  of  the  plates  smooth,  their 
contour  rather  strongly  convex  in  mature  individuals,  with  the  sutures  im- 
pressed; the  base  bilobed  by  reason  of  the  impressed  suture  that  separates  the 
two  plates;  the  radial  plates  diverging  more  or  less  from  the  base  to  the  top 
of  the  dorsal  cup ;  the  anal  plate  similar  in  form  and  size  to  the  radials.  The 
tegmen  higher  than  or  lower  than  the  dorsal  cup,  with  a  large  central  plate 


PALEONTOLOGY  339 

whose  surface  is  elevated  into  a  prominent  node  that  is  somewhat  flattened 
antero-posteriorly ;  the  ambulacral  regions  rounded,  sloping  away  from  the 
border  of  the  central  plate  in  the  form  of  five  shoulders  made  up  of  numerous 
small  plates,  from  two  to  five  of  which  in  each  ray  bear  low  tubercles;  the 
interambulacral  regions  are  depressed  and  four  of  them  are  rounded  furrows 
which  curve  downwards  to  the  margin  of  the  dorsal  cup ;  the  posterior  inter- 
radius  broader  than  the  others,  somewhat  protuberant  medially,  the  anus 
situated  well  up  towards  the  large  central  plate,  and  directed  laterally  or 
obliquely  upward.    The  arms  unknown. 

Remarks. — So  far  as  the  dorsal  cup  is  concerned  it  is  absolutely  impos- 
sible to  distinguish  this  species  from  T.  inflatus,  and  neither  of  these  species 
can  be  separated  from  T.  cornigerus.  The  only  distinguishing  character  of 
T.  trijugis  as  compared  with  T.  inflatus,  is  found  in  the  greater  convexity  of 
the  plates  in  the  ambulacral  regions  of  the  tegmen,  a  number  of  these  plates 
in  each  ray  being  raised  into  distinct  tubercles.  Such  characters  as  these 
are  of  very  slight  value  among  camerate  crinoids,  and  it  is  doubtful  whether 
such  a  difference  is  of  even  specific  importance.  Talarocrinus  cornigerus, 
another  related  species,  has  these  same  plates  developed  into  distinct,  short 
spines,  in  other  respects  being  entirely  like  T.  inflatus  and  T.  trijugis.  Not 
one  specimen  in  a  thousand  of  any  of  these  species  preserves  the  tegmen  in 
such  a  condition  that  its  characters  can  be  recognized,  but  so  far  as  observa- 
tions have  been  possible  the  specimens  from  Monroe  and  Randolph  counties 
are  mostly  referable  to  T.  inflatus,  although  one  good  specimen  has  well 
developed  spines  and  may  be  referred  to  T.  cornigerus.  In  Hardin  County 
T.  trijugis  seems  to  be  the  commoner  form,  but  in  Union  County  a  number 
of  good  specimens  preserving  the  tegmen  have  been  collected  from  the  same 
horizon,  which  represent  both  T.  inflatus  and  T.  trijugis. 

By  his  method  of  matching  individuals,  Ulrich  has  come  to  the  conclu- 
sion that  the  "Upper  Ohara"  of  Hardin  County  is  not  the  equivalent  of  the 
Renault  of  Monroe  County,  because  he  has  not  found  the  same  Talarocrinus 
in  both;  but  the  fact  that  both  the  Hardin  County  and  Monroe  County  forms 
are  found  together  in  Union  County,  and  T.  inflatus  is  also  present  in  Hardin 
County,  makes  it  clear  that  the  individual  characteristics  of  which  Ulrich 
has  made  use  are  of  less  value  for  correlation  purposes  than  the  larger  generic 
characters.  Furthermore,  it  is  altogether  probable  that  the  characters  of  all 
three  of  these  species  would  be  found  to  merge  together  in  all  of  the  localities 
if  a  sufficient  number  of  specimens  were  available  for  study.  Every  student 
who  has  given  any  considerable  attention  to  the  study  of  the  camerate  crinoids 
knows  how  inconsequential  are  such  characters  as  those  which  distinguish 
these  species.  At  the  most,  they  probably  represent  contemporaneous  geo- 
graphic variations  of  a  single  form. 

Horizon  and  locality.— -Renault  limestone,  Hardin.  Pope,  and  Union 
counties,  Illinois. 


340  GEOLOGY  OF  HARDIN  COUNTY 

Talabocbinus  coenigeeus   (Shumard) 

Plate  VI,  Fig.  35 
1857.     Dichocrinus  cormgerus  Shumard,  Trans.  St.  Louis  Acad.  Sci.,  vol.  1, 

p.  72,  pi.  1,  figs.  la-c. 
1897.     Talarocrinus  cormgerus  Wachsmuth  and    Springer,   N".   Amer.   Crin. 

Camer.,  p.  783,  pi.  78,  figs.  6a-b,  7a-b. 
1918.     Talarocrinus  cornigerus  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West. 

Ky.,  pi.  8,  figs.  18-19,  pi.  9,  figs.  7-9. 
Talarocrinus  cornigerus  was  originally  described  as  coming  from  the 
"Mountain  limestone/'  and  Wachsmuth  and  Springer  referred  it  to  the  St. 
Louis  limestone.  It  has  been  determined  by  Ulrich,  however,  that  the  type 
specimen  is  from  the  Lower  Chester,  and  Wachsmnth  and  Springer's  refer- 
ence of  the  species  to  the  St.  Louis  limestone  was  erroneous.  In  the  characters 
of  its  dorsal  cup  the  species  is  identical  with  T.  inflatus  and  T.  trijugis.  In 
all  of  these  species  the  cup  varies  considerably,  in  general  it  is  bowl-shaped, 
but  occasionally  an  individual  is  met  with  in  which  the  radial  plates  flare  out 
in  such  a  manner  as  to  be  essentially  like  that  of  T.  sexlobatus.  The  differ- 
ences between  these  three  species,  as  has  already  been  pointed  out,  are  found 
in  the  relative  development  of  spines  upon  the  ambulacral  plates  of  the 
tegmen,  these  being  best  developed  in  T.  cornigerus,  and  least  strongly  de- 
veloped in  T.  inflatus,  with  T.  trijugis  occupying  an  intermediate  position. 
There  is  no  evidence  that  these  characters  have  different  time  values,  and  if 
they  are  of  value  at  all  it  is  as  contemporaneous  geographic  variations.  The 
specimen  illustrated  is  from  the  Renault  limestone  in  Randolph  County, 
the  same  horizon  in  which  the  typical  T.  inflatus  is  known.  T.  trijugis  and 
T.  inflatus  occur  together  in  Union  County,  and  this  association  with  the 
demonstrated  contemporaneity  of  T.  inflatus  and  T.  cornigerus  in  Randolph 
and  Monroe  counties,  demonstrates  the  time  equivalence  of  these  Talarocrinus 
beds  across  the  entire  state. 

Horizon   and   locality. — Renault   limestone,   Randolph    County,   Illinois. 

Talabocbinus  ovatus  Worthen 

Plate  VI,  Figs.  27-33 
1883.  Talarocrinus  ovatus  Worthen,  Geol.  Surv.  111.,  vol.  7,  p.  314,  pi.  29, 
fig.  11. 
Description. — Body,  when  complete  without  the  arms,  subovoid  in  form, 
higher  than  wide.  The  dimensions  of  the  holotype  are:  height  17.3  mm., 
greatest  width  12.6  mm.,  height  of  dorsal  cup  9.1  mm.,  greatest  width  of 
base  8.3  mm.  Dorsal  cup  bowl-shaped,  the  surface  of  the  plates  smooth  and 
convex  with  the  sutures  impressed,  the  base  bilobed  by  reason  of  the  impres- 
sion of  the  sutures  between  the  two  plates.  The  radial  plates  higher  than 
wide,  a  little  wider  at  the  upper  margin  than  at  the  junction  with  the  base. 


PALEONTOLOGY  341 

which  causes  the  sides  of  the  cup  to  diverge  slightly  from  the  base  to  the  arm 
openings.  Anal  plate  similar  in  form  and  size  to  the  radials  but  with  the 
lateral  margins  more  nearly  parallel.  Tegmen  not  so  high  as  the  dorsal  cup, 
dome-shaped,  its  center  occupied  by  a  plate  somewhat  larger  than  those  about 
it,  and  produced  into  a  short  but  rather  slender  thorn-like  spine;  from  the 
central  spinose  plate  the  ambulacra  radiate  as  five  rounded,  shoulder-like 
lobes,  towards  the  outer  border  of  the  tegmen  above  the  arm  openings,  the 
anterior  and  anterolateral  ambulacra  each  includes  a  plate  which  tends  to  be 
raised  into  a  short,  thorn-like  spine  smaller  than  that  upon  the  central  plate, 
some  of  the  other  plates  are  also  nodose  in  some  individuals,  but  the  postero- 
lateral ambulacra  are  less  rugose  than  the  others.  The  interambulacral  spaces 
scarcely  depressed  towards  the  center,  but  distally  they  become  a  little  de- 
pressed below  the  ambulacra  and  the  surface  curves  regularly  downward  into 
the  dorsal  cup.  The  posterior  interambulacral  area  is  much  broader  than  the 
others,  and  a  broadly  rounded  ridge  made  up  of  small  plates  leads  upward 
from  the  anal  plate  towards  the  central  spine-bearing  plate  of  the  tegmen, 
the  anal  opening  is  situated  well  up  towards  the  median  plate  and  is  directed 
obliquely  upward  and  outward.     Arms  not  known. 

Remarks. — The  dorsal  cup  of  this  species  resembles  T.  inflatus,  T. 
trijugis,  and  T.  cornig&rus,  but  in  the  specimens  which  have  been  studied,  its 
sides  seem  to  be  somewhat  more  erect  than  in  those  species  and  proportionally 
a  little  higher.  The  characters  of  the  tegmen  exhibit  greater  differences. 
The  rather  massive  central  plate  of  the  tegmen  in  those  species,  with  its 
antero-posteriorly  flattened  node,  is  represented  by  the  comparatively  much 
smaller  plate  surmounted  by  only  a  slender,  thorn-like  spine.  In  those 
species,  also,  all  five  of  the  ambulacra  tend  to  be  similar  in  the  development 
of  nodes  and  spines  upon  the  plates,  but  this  species,  like  T.  planus,  seems 
to  have  the  postero-lateral  ambulacra  less  nodose  than  the  three  anterior 
ones,  although  as  in  all  camerate  crinoids,  the  development  of  spines  and 
nodes  exhibits  a  considerable  degree  of  variation,  and  all  too  few  examples 
preserving  these  characters  are  available  for  study. 

The  specimen  from  Breckenridge  County,  Kentucky,  illustrated  by  Ulrich 
as  T.  ovatus1  possesses  a  massive,  flattened,  central  tegminal  plate,  and  cer- 
tainly is  not  correctly  identified,  it  being  more  nearly  related  to  the  T.  inflatus 
and  its  allies. 

In  the  original  definition  of  the  species  by  Worthen,  it  is  recorded  as 
coming  from  the  Chester  limestone  of  Monroe  County,  Illinois,  and  Ulrich 
has  assumed  that  it  came  from  the  Renault  limestone.  No  authentic  example, 
however,  has  been  collected  from  known  Renault  beds,  but  a  very  good  speci- 
men has  been  collected  from  the  Paint  Creek  formation  of  Monroe  County, 
and  it  is  not  unlikely  that  Worthen's  holotype  also  came  from  this  horizon. 

Horizon  and  locality. — Paint  Creek  formation,  Monroe  County,  Illinois. 

1  Ulrich,  Ky.  Geol.   Surv.,  Miss.  Form.  West.  Ky.,  pi.   8,  figs.   16-17. 


342  GEOLOGY    OF    HARDIN    COUNTY 

Talarocrinus  planus  n.  sp. 

Plate  VI,  Figs.  14-16 

Description. — Body,  when  complete  without  the  arms,  subovoid  in  form, 
higher  than  wide,  the  dorsal  cup  higher  than  the  tegmen.  The  dimensions  of 
the  holotype  are:  height  13.7  mm.,  greatest  width  11.7  mm.,  height  of  dorsal 
cup  7.6  mm.  Dorsal  cup  deep  bowl-shaped,  the  surfaces  of  the  plates  smooth, 
the  sutures  not  impressed.  The  base  bowl-shaped,  not  bilobate.  Radial  plates 
as  high  or  higher  than  wide,  their  lateral  margins  slightly  diverging  so  that 
the  sides  of  the  cup  diverge  gently  from  the  top  of  the  basal  plates  to  the  arm 
bases.  The  anal  plate  similar  to  the  radials  in  form  and  size.  Costal  plates 
one  in  each  ray,  very  broadly  triangular  in  form,  supporting  two  series  of 
distichals.  Tegmen  distinctly  pentalobate,  the  plate  occupying  the  central 
position  is  the  largest;  in  the  type  specimen  one  ambulacral  plate  of  the 
anterior  ray  is  produced  into  a  short,  thorn-like  spine,  the  corresponding 
plates  in  the  two  anterolateral  rays  are  less  produced  but  are  distinctly  nodose. 
the  same  plates  in  the  postero-lateral  rays  are  not  produced  at  all.  Four  of 
the  interambulacral  areas  are  distinctly  depressed  and  appear  as  narrow, 
rounded  furrows  leading  downward  from  the  center  of  the  tegmen  between 
the  arm  bases;  the  posterior  interambulacral  area  is  much  broader  than  the 
others,  its  surface  depressed  between  the  adjacent  ambulacra,  with  a  distinct 
rounded  elevation  leading  upward  to  the  anal  opening  which  is  situated  at  the 
extremity  of  a  short  tube  whose  upper  extremity  extends  a  little  above  the 
central  plate  of  the  tegmen,  the  anal  opening  directed  obliquely  outward  and 
upward.  Arm  openings  two  in  each  ray,  arms  unknown,  but  doubtless  four 
from  each  ray  as  in  other  species  of  the  genus  so  far  as  known. 

Remarks. — This  species  differs  notably  from  T.  cornigerus,  T.  trijugis 
and  T.  infiatus  in  the  absence  of  the  distinctly  bilobed  base,  in  the  even 
surface  of  the  dorsal  cup,  and  in  the  smaller  and  less  protuberant  central 
plate  of  the  tegmen.  The  form  of  the  body  is  more  like  T.  butt  si  from  the 
Shetlerville  formation  than  any  other  member  of  the  genus,  but  the  tegmen 
is  much  more  conspicuously  lobate,  with  more  prominent  arm  bases,  the 
tegmen  being  more  like  that  of  T.  dewolfi. 

The  species  is  of  especial  interest  because  its  relationships  are  with 
T.  buttsi  and  T.  dewolfi,  two  species  named  by  Ulrich  from  the  "Upper 
Ohara"  and  consequently  referred  to  the  Ste.  Genevieve  by  him,  while  this 
species  is  from  the  Paint  Creek  formation  of  Randolph  County. 

Horizon  and  locality. — Paint  Creek  formation,  Randolph  County,  Illinois. 

Pterotocrinus  serratus  n.  sp. 

Plate  V,  Figs.  24-26 
Description. — This  species  is  based  on  the  "wing  plates"  only,  which  are 
subspatulate  in  form.     The  lateral  margins  are  subparallel  proximally  but 


PALEONTOLOGY  343 

become  more  or  less  widely  divergent  distally,  being  unevenly  concave  in 
outline.  The  distal  margin  is  more  or  less  arcuate  or  nearly  straight,  the 
plates  becoming  very  thin  distally  and  being  divided  by  incisions  of  varying 
depths  into  a  series  of  serrations.  The  dimensions  of  the  holotype  are: 
length  of  "wing  plate"  11.2  mm.,  greatest  width  distally  7.7  mm.  Another 
specimen  with  a  length  of  about  12.5  mm.,  has  a  maximum  width  of  about 
11.5  mm. 

Remarks. — The  genus  Pterotocrinus  is  very  common  in  many  of  the 
Chester  faunas,  but  the  species  are  rarely  represented  by  complete  specimens, 
and  the  detached  "wing  plates"  are  the  parts  commonly  met  with.  For- 
tunately the  variations  of  these  highly  specialized  plates  furnish  some  of  the 
best  of  specific  characters  in  the  genus,  so  that  it  is  practicable  to  define 
species  from  these  plates  alone.  The  genus  is  not  known  in  the  Eenault 
faunas,  but  it  makes  its  appearance  in  the  Paint  Creek,  and  continues  through 
all  of  the  higher  fossiliferous  horizons  of  the  Chester  unless  it  be  the  CI  ore 
and  Kinkaid.  A  rather  common  form  in  the  Paint  Creek,  both  in  the  typical 
exposures  of  the  formation  in  Monroe  and  St.  Clair  counties,  and  in  Johnson 
County,  is  this  form  of  "wing  plate"  with  the  thin,  knife-like  distal  edge 
which  is  distinctly  but  more  or  less  irregularly  serrate. 

Horizon  and  locality. — Paint  Creek  formation,  St.  Clair,  Monroe,  Ean- 
dolph,  and  Johnson  counties,  Illinois. 

Pachylocrinus  cachensis  n.  sp. 

Plate  VIII,  Fig.  35 
Description. — Dorsal  cup  low  basin-shaped,  with  the  base  excavated  and 
the  sides  broadly  flaring,  the  arms  of  moderate  length.  The  dimensions  of 
the  holotype  are:  diameter  of  dorsal  cup  8.3  mm.,  depth  of  dorsal  cup  3  mm., 
height  of  crown  from  base  to  tips  of  arms,  25.5  mm.  The  length  of  the  arms 
would  be  somewhat  greater  if  they  were  perfectly  preserved.  Underbasal 
plates  small,  entirely  included  in  the  basal  concavity,  but  only  partially 
covered  by  the  column.  The  basal  plates  about  as  wide  as  long,  their  proximal 
portions  occupying  the  sloping  sides  of  the  basal  concavity.  The  radial  plates 
wider  than  high.  Eadianal  plate  much  longer  than  wide,  pentagonal  in  out- 
line, the  longer  sides  diverging  ventrally,  the  ventral  side  short  and  sup- 
porting the  first  tube  plate.  Anal  plate  smaller  than  the  radianal,  resting 
upon  the  truncate  margin  of  the  posterior  basal  and  lying  between  the 
radianal  and  first  tube  plate  on  the  right,  and  the  left  postero-lateral  radial 
on  the  left.  Each  ray  with  a  single  costal  which  is  larger  than  the  radial  and 
is  spine-bearing,  the  spine  rising  from  close  up  to  the  angular  distal  extremity 
of  the  plate.  The  distichals,  except  the  first  and  last  in  each  series,  quad- 
rangular, wider  than  long,  nearly  rectangular  or  slightly  wedge-shaped,  com- 
monly six  in  each  series,  but  one  series  of  thirteen  is  present  in  the  holotype; 
the  axillary  plate  in  each  series  is  larger  and  thicker  than  the  others,  and  is 


344  GEOLOGY    OF    HARDIN    COUNTS 

extended  into  a  short  spine.  One  or  two  divisions  of  the  rays  occur  beyond 
the  distichals,  the  plates  are  similar  to  the  distichals  but  smaller,  and  towards 
the  tips  of  the  arms  they  become  more  wedge-shaped,  each  axillary  plate 
is  larger  and  thicker  than  the  others,  and  is  produced  into  a  node  or  short 
spine. 

Remarks. — This  species  is  allied  to  P.  spinifera  (Wetherby),  from  the 
Chester  of  Pulaski  County,  Kentucky,  probably  the  Glen  Dean  formation,  but 
it  is  smaller  and  much  smoother  in  appearance,  with  shorter  axillary  spines 
in  the  brachial  series,  and  with  the  brachial  plates  much  less  wedge-shaped. 

The  holotype  and  one  or  two  other  good  specimens  are  from  the  Cache 
River  bluffs  in  Johnson  County,  but  the  same  species  is  present  in  the  Paint 
Creek  formation  in  Monroe  County,  Illinois. 

Horizon  and  locality. — Paint  Creek  formation,  Cache  River  bluffs  six 
miles  south  of  Vienna,  Johnson  County,  and  two  miles  south  of  Columbia, 
Monroe  County,  Illinois. 

Agassizocrinus  dissimilis  n.  sp. 

Plate  V,  Figs.  29-30 

Description. — Dorsal  cup  subhemispherical.  The  dimensions  of  the 
holotype  are :  greatest  width  13.7  mm.,  height  10.8  mm.  Surfaces  of  the 
plates  convex,  with  the  bounding  sutures  distinctly  impressed.  The  under- 
basals  anchylosed  into  a  large  pentagonal  plate  with  gently  convex  surface, 
which  is  the  largest  plate  in  the  cup.  Basals  wider  than  high,  resting  upon 
the  nearly  straight  or  slightly  concave  faces  of  the  pentagonal  underbasal. 
disc.  Radial  plates  short  and  broad,  their  width  being  twice  or  more  than 
twice  their  height.  Radianal  plate  quadrangular,  rather  large.  Anal  plate 
smaller  than  the  radianal,  its  contact  with  the  posterior  basal  very  short. 
Arms  unknown. 

Remarks. — This  species  is  especially  characterized  by  the  shortness  of 
the  dorsal  cup  and  by  the  convexity  of  the  plates  and  consequently  impressed 
sutures. 

Horizon  and  locality. — Paint  Creek  formation,  one  and  one-fourth  miles 
northwest  of  Floraville,  St.  Clair  County,  Illinois. 

Genus  ARCHIMEDES 

The  genus  Archimedes  is  one  of  the  very  characteristic  members  of  most 
Chester  faunas,  the  main  mass  of  the  Chester  limestone  being  originally 
described  as  the  "Archimedes  limestone"  by  the  earlier  geologists  working  in 
the  Mississippi  and  Ohio  valleys.  As  commonly  preserved  only  the  axes  of  the 
colonies  are  found,  and  these  exhibit  such  a  wide  range  of  variation  that  it 
is  exceedingly  difficult  to  draw  lines  between  specific  groups.  Ulrich  is 
responsible  for  most  of  the  named  species   of  the  genus,  and  while  many 


PALEOXTOLOGY  345 

examples  in  the  large  collections  that  have  been  made  do  resemble  more  or 
less  closely  the  illustrations  of  his  several  species,  and  may  be  identified,  there 
are  many  other  examples  that  cannot  be  made  to  fit  satisfactorily  in  any  of 
the  named  species.  It  is  altogether  likely  that  the  fenestrated  expansions 
from  the  axes  would  supply  much  more  satisfactory  specific  characters  if 
these  characters  could  be  observed,  but  they  can  be  determined  in  rare  cases 
only.  In  the  arrangement  of  the  zooecia,  the  fenestrated  portion  of  Archi- 
medes is  identical  with  Fenestella,  but  the  branches  are  commonly  finer  and 
more  numerous,  and  the  fenestrules  are  shorter,  so  that  the  whole  net-like 
expansion  is  notably  finer  than  in  most  species  of  Fenestella. 

The  genus  Archimedes  is  met  with  in  essentially  all  fossil-bearing 
Chester  horizons  in  Illinois,  but  the  genus  rarely  occurs  in  the  Renault  of 
Monroe  and  Randolph  counties,  and  it  is  likewise  a  rare  member  of  the 
Shetlerville  and  Renault  faunas  in  Hardin  County  and  the  adjacent  parts  of 
Illinois  and  Kentucky.  The  genus  first  became  a  common  form  in  the  faunas 
of  the  Paint  Creek,  this  being  true  both  in  the  Mississippi  Valley  counties  in 
Illinois  and  in  the  more  southeastern  portions  of  the  state. 

On  the  accompanying  plate  VII  a  number  of  forms  of  the  genus  from 
the  Paint  Creek  formation  of  Johnson  County  are  illustrated.  The  specific 
identifications  are  made  with  some  hesitation,  as  is  always  the  case  in  this 
genus,  but  these  specimens  seem  to  be  reasonably  like  the  figures  of  the 
species  they  have  been  identified  with,  as  they  have  been  illustrated  by 
Ulrich.  These  several  forms  are  introduced  in  this  place  in  order  to  show 
the  variety  exhibited  by  members  of  this  genus  in  the  Paint  Creek  formation 
in  southeastern  Illinois,  in  contrast  with  the  scarcity  of  the  genus  in  the 
Renault.  This  same  contrast  between  the  two  equivalent  faunas  is  likewise 
exhibited  in  Monroe  and  Randolph  counties. 

Archimedes  cf.  savallovanus  Hall 

Plate  VII,  Fig.  26 
1857.     Fenestella    (Archimedes)    Sivallovana   Hall,   Proc.   Amer.    Ass.   Adv. 

Sci.,  vol.  10,  p.  178. 
1890.  Archimedes  swallovanus  Ulrich,  Geol.  Surv.  111.,  vol.  8,  p.  574,  pi. 
63,  figs.  12-12d. 
The  axes  that  are  referred  to  this  species  are  stouter  forms  than  the 
others  that  are  illustrated  on  the  same  plate.  This  species  is  more  common 
in  the  Middle  Chester  formations,  and  these  Lower  Chester  examples  are 
somewhat  more  slender,  with  flanges  somewhat  more  closely  arranged  than 
in  the  more  typical  representatives  of  the  species. 

Horizon  and  locality. — Paint   Creek  formation,   Cache  River  bluff,  six 
miles  south  of  Vienna,  Johnson  County,  Illinois. 


346  GEOLOGY    OF    HARDIN    COUNTY 

Archimedes  compactus  Ulrich 

Plate  VII,  Fig.  27 
1890.     Archimedes  compactus  Ulrich,  Geol.  Surv.  111.,  vol.  8,  p.  572,  pi.  63, 
figs.  2-2b,  2d-e. 

The  axes  of  this  species  of  Archimedes  may  attain  a  length  of  30  to  40 
mm.,  and  when  well  preserved  they  commonly  exhibit  a  slight  taper  towards 
each  extremity.  There  are  commonly  from  nine  to  twelve  flanges  present 
in  the  space  of  2  cm.  This  type  of  axis  is  not  uncommonly  present  in  the 
Paint  Creek  fauna  of  Monroe  County,  as  well  as  in  the  more  southern  part 
of  Illinois. 

Horizon  and  locality. — Paint  Creek  formation,  Cache  River  bluff,  six 
miles  south  of  Vienna,  Johnson  County,  Illinois. 

Archimedes  proutanus  Ulrich 

Plate  VII,  Fig.  28 
1890.     Archimedes  proutanus  Ulrich,  Geol.  Surv.  111.,  vol.  8,  p.  576,  pi.  63, 
figs.  3-3d. 
This  species  is  characterized  by  a  rather  slender  axis,  with  from  six  to 
eight  flanges  in  the  space  of  2  cm.     From  the  border  of  the  flange  the  slope 
towards  the  axis  is  abrupt  above,  and  more  gentle  and  concave  below. 

Horizon  and  locality. — Paint  Creek  formation,  Cache  River  bluff,  six 
miles  south  of  Vienna,  Johnson  County,  Illinois. 

Archimedes  distans  Ulrich 

Plate  VII,  Fig.  29 

1890.  Archimedes  distans  Ulrich,  Geol.  Surv.  111.,  vol.  8,  p.  578,  pi.  63, 
figs.  9-9b. 
As  its  name  suggests  this  species  is  loosely  coiled,  with  about  four  volu- 
tions in  the  distance  of  2  cm. ;  the  central  portion  of  the  axis  is  rather 
slender,  with  the  lower  slope  from  the  rim  of  the  flange  long,  gentle  and  con- 
cave, and  the  upper  slope  abrupt. 

Horizon  and  locality. — Paint  Creek  formation,  Cache  River  bluff,  six 
miles  south  of  Vienna,  Johnson  County,  Illinois. 

Archimedes  meekanus  Hall 

Plate  VII,  Fig.  30 
1857.     Fenestella  (Archimedes)  Meekana  Hall,  Proc.  Amer.  Ass.  Adv.  Sci., 

vol.  10,  p.  178. 

1890.     Archimedes  meekanus  Ulrich,  Geol.  Snrv.  111.,  vol.  8,  p.  578,  pi.  63, 
fig.  4. 

This  is  a  slender  species  with  from  five  to  six  volutions  in  the  space  of 
2  cm.,  in  which  the  slope  from  the  rim  of  the  flange  to  the  central  portion 


PALEONTOLOGY  347 

of  the  axis  is  more  nearly  symmetrical  above  and  below  than  in  other  species 
with  similar  proportions. 

Horizon  and  locality. — Paint  Creek  formation,  Cache  Eiver  bluff,  six 
miles  south  of  Vienna,  Johnson  County,  Illinois. 

Archimedes  communis  Ulrich 

.      Plate  VII,  Figs.  31-32 
1890.     Archimedes  communis  Ulrich,  Geol.  Surv.  111.,  vol.  8,  p.  573,  pi.  63, 
figs.  1-ld. 

This  is  another  one  of  the  rather  slender  species,  with  about  seven  or 
eight  volutions  in  the  space  of  2  cm.  The  slopes  from  the  rim  of  the  flange 
to  the  central  portion  of  the  axis  is  nearly  symmetrical  above  and  below,  but 
the  flange  is  considerably  more  extended  than  in  A.  meekanus,  and  the  volu- 
tions are  closer  together.  Examples  of  the  axis  of  this  species  are  commonly 
more  elongate  than  those  of  some  other  species,  and  it  is  possible  that  this 
greater  length  is  one  of  the  specific  characters. 

Horizon  and  locality. — Paint  Creek  formation,  Cache  Eiver  bluff,  six 
miles  south  of  Vienna,  Johnson  County,  Illinois. 

Lyropora  quincuncialis  Hall 

Plate  VII,  Figs.  5-6 
1857.     Fenestella  (Lyropora)  quincuncialis  Hall,  Proc.  Amer.  Ass.  Adv.  Sci., 

vol.  10,  p.  180. 
1890.     Lyropom.  quincuncialis  Ulrich,  Geol.  Surv.  111.,  vol.  8,  p.  583,  pi.  55, 

^ngs.  7-7c,  pi.  58,  figs.  3-3d. 
Species  of  Lyropora  occur  commonly  in  the  higher  beds  of  the  "Upper 
Ohara"  in  Hardin  County  and  elsewhere,  and  the  genus  occurs,  though  less 
frequently,  in  the  Shetlerville  formation,  which  is  the  lower  portion  of  the 
''Upper  Ohara."  The  original  of  figure  5  of  the  accompanying  plate  is  one 
of  several  examples  from  a  Shetlerville  exposure  about  one  mile  south  of 
Eichorn.  Some  of  the  specimens  exhibit  the  characters  of  the  fenestrated 
portion  of  the  colonies,  and  they  possess  about  25  branches  in  the  space*  of 
1  cm.,  and  20  fenestrules  in  the  same  space.  The  zooecia  are  arranged  mainly 
in  two  series  along  the  branches,  and  the  median  line  of  the  branches  is 
marked  by  a  series  of  low  nodes.  These  characters  do  not  differ  in  any  essen- 
tial respect  from  the  illustrations  of  L.  quincuncialis  given  by  Ulrich  in  vol. 
8  of  the  Geological  Survey  of  Illinois,  except  that  there  are  a  few  more 
fenestrules  in  the  unit  distance,  the  number  given  by  Ulrich  being  16  or  17, 
instead  of  the  20  which  our  specimens  possess.  In  view  of  the  close  agree- 
ment in  all  other  characters,  however,  this  slight  variation  cannot  be  con- 
sidered as  being  sufficient  to  exclude  the  specimens  from  this  well  known 
Chester   species.      The   original   of   the  larger   figure    (fig.   6),   is  from   the 


348  GEOLOGY    OF    HARDIN    COUNTY 

Renault  portion  of  the  "Upper  Ohara"  at  Cedar  Bluff,  near  Princeton. 
Kentucky,  the  type  locality  of  the  Ohara.  In  this  specimen  the  reverse  side 
of  the  fenestrated  part  of  the  colony  is  well  exhibited,  and  it  has  20  fenestrules 
and  26  branches  in  the  unit  distance  of  1  cm.,  being  essentially  like  the 
Eichorn  specimens  in  this  respect. 

This  species  of  Lyropora  is  a  common  one  in  the  typical  Renault  lime- 
stone in  Monroe  and  Randolph  counties,  and  although  the  genus  occurs  all 
through  the  Chester,  it  is  especially  common  in  the  iower  Chester  formations. 
On  the  other  hand  the  most  diligent  search  for  many  years  has  never  brought 
to  light  a  single  example  of  Lyropora  in  the  Ste.  Genevieve  limestone,  al- 
though the  genus  is  known  in  beds  as  old  as  the  Burlington  limestone.  This 
is  one  of  the  characters  which  may  be  classed  among  the  "complexion"  features 
of  the  "Upper  Ohara,"  which  ties  it  to  the  Chester  and  excludes  it  from  the 
Ste.  Genevieve,  and  even  though  a  sporadic  specimen  of  Lyropora  should  be 
found  sometime  in  the  Ste.  Genevieve,  it  would  not  overthrow  the  relation- 
ships of  the  faunas  any  more  than  the  finding  of  Septopora  in  the  St.  Louis 
limestone  makes  that  formation  Chester.  Furthermore,  these  "Upper  Ohara" 
specimens  of  Lyropora  are  identical  with  forms  in  the  topical  Renault  lime- 
stone elsewhere. 

Horizon  and  locality. — Shetlerville  formation,  one  mile  south  of  Eichorn. 
Hardin  County,  Illinois.  Renault  limestone,  Monroe,  Randolph,  and  Hardin 
counties,  Illinois,  Ste.  Genevieve  County,  Missouri,  and  near  Princeton, 
Kentucky. 

Septopora  similis  n.  sp. 

Plate  VII,  Figs.  1-4 

Description. — Zoarium  flabelliform,  fiat  or  undulating,  consisting  of 
nearly  uniform  branches  united  by  dissepiments  which  are  somewhat  narrower 
than  the  branches  themselves;  most  of  the  dissepiments  are  nearly  straight, 
some  are  more  or  less  oblique,  and  a  few  are  slightly  arched.  Branches  in- 
creasing by  bifurcation  or  intercalation  .5  mm.  or  less  in  width,  from  10  to 
12  occupying  the  space  of  1  cm.  Fenestrules  from  10  to  12  in  the  space  of 
1  ®ni.,  more  or  less  nearly  rectangular,  rhomboidal  or  crescentic  in  form,  with 
the  length  and  breadth  subequal.  The  zooecia  commonly  in  two  or  rarely 
three  rows,  from  21  to  22  occupy  the  space  of  5  mm.,  from  3  to  6  present  upon 
each  dissepiment;  the  apertures  subcircular,  their  distance  apart  about  equal 
to  their  diameter,  the  peristome  scarcely  elevated  above  the  surface  of  the 
branch.  The  obverse  side  of  the  branches  with  an  inconspicuous  or  essentially 
obsolete  keel,  and  with  low,  inconspicuous  median  tubercles  at  intervals  about 
equal  to  the  distance  between  the  dissepiments.  Reverse  side  finely  striate, 
the  supplementary  pores  inconspicuous. 

Remarks. — This  species  resembles  Septopora  subquadrans  in  the  dimen- 
sions of  its  branches  and  fenestrules  and  in  the  arrangement  and  number  of 


PALEONTOLOGY  349 

the  zooecia,  but  the  dissepiments  are  less  commonly  arched.  It  differs  from 
that  species  especially  in  the  much  less  conspicuous  median  keel  and  tubercles 
upon  the  obverse  side  of  the  branches,  and  in  the  smaller  number  of  zooecia 
upon  the  dissepiments.  The  zooecia  are  also  smaller  and  have  much  less 
prominent  peristomes  than  S.  sub quadr arts. 

The  description  of  this  species  is  introduced  here  because  of  its  bearing 
upon  one  line  of  evidence  that  Ulrich  has  used  in  his  contention  for  the 
Chester  age  of  the  Ste.  Genevieve.  Attention  is  drawn  by  him1  to  the  fact 
that  the  bryozoan  Coeloconus,  which  is  not  uncommon  in  a  number  of  the 
Chester  formations,  is  represented  by  a  species  in  the  undoubted  Ste.  Genevieve 
limestone  of  Monroe  County,  Illinois,  and  elsewhere,  his  assumption  being 
that  the  presence  of  this  particularly  characteristic  Chester  genus  in  the  Ste. 
Genevieve  limestone  fauna,  is  evidence  for  uniting  the  Ste.  Genevieve  with 
the  Chester.  As  it  has  been  known  in  the  past,  the  genus  Septopora  is  an 
especially  characteristic  genus  of  the  Chester  faunas,  and  nowhere  in  the 
literature  has  any  member  of  the  genus  been  recorded  from  strata  older  than 
the  Chester.  The  species  here  described,  however,  is  from  the  St.  Louis  lime- 
stone, and  was  collected  by  the  writer  from  the  lower  portion  of  this  forma- 
tion, in  the  Mississippi  River  bluffs  above  Little  Rock,  Ste.  Genevieve  County, 
Missouri.  If  the  presence  of  a  species  of  Coeloconus  in  the  Fredonia  lime- 
stone is  evidence  for  the  inclusion  of  that  formation  in  the  Chester  group, 
then  why  is  not  the  presence  of  a  species  of  Septopora  in  the  lower  portion  of 
the  St.  Louis  limestone  evidence  for  placing  the  base  of  the  Chester  still  lower 
in  the  stratigraphic  series,  and  the  inclusion  of  the  St.  Louis  limestone  also, 
in  the  Chester?  Such  an  extension  of  the  Chester  would,  of  course,  never  be 
advocated. 

The  facts  concerning  these  two  genera  of  bryozoans  simply  go  to  show 
that  our  knowledge  of  the  geologic  range  of  genera  and  species  of  fossils  is 
incomplete.  As  observations  are  extended,  other  genera  now  known  only  in 
the  Chester  may  be  found  to  be  present  in  the  Ste.  Genevieve  or  older  forma- 
tions, but  such  discoveries  will  not  affect  the  correlation  of  the  formations. 
The  paleontologic  basis  for  the  correlation  of  formations  within  one  basin  of 
sedimentation,  must  be  the  sum  total  of  the  characters  of  the  faunas  involved, 
in  other  words  the  complete  faunal  association,  or  the  general  "complexion" 
of  the  life  of  a  formation  is  of  far  greater  importance  than  the  sporadic 
occurrence  of  an  unusual  genus,  or  the  evidence  afforded  by  the  method  of 
matching  individuals  irrespective  of  other  lines  of  evidence. 

Horizon  and  locality. — St.  Louis  limestone,  lower  part,  above  Little 
Rock,  Ste.  Genevieve  County,  Missouri. 

*Ky.  Geol.  Surv.,  Miss.  Form.  West.  Ky.,  pi.  11,  figs.   11-13. 


350  GEOLOGY    OF    HARDIN    COUNTY 

Cystodictya  labiosa  n.  sp. 

Plate  VII,  Figs.  7-24 

Description. — Zoarium  ramose,  with  flattened,  bifoliate,  ribbon-like 
branches  2.5  to  3  mm.  in  width,  bifurcating  or  giving  off  lateral  branches  at 
irregular  intervals  varying  from  2  to  9  or  10  mm.  apart,  with  well  defined, 
non-poriferous  margins.  Zooecia  arranged  in  more  or  less  regular  diagonal 
rows  with  from  7  to  10  apertures  in  each  row,  in  places  the  apertures  seem 
to  be  in  two  sets  of  diagonals  starting  from  the  two  margins  and  becoming 
confused  in  the  central  portion  of  the  zoarial  surface ;  the  linear  arrangement 
of  the  apertures  is  much  less  noticeable  than  the  diagonal.  The  apertures 
have  a  raised  peristome,  giving  them  the  appearance  of  being  situated  on 
low  pustules,  the  distal  margins  of  the  peristomes  commonly  a  little  more 
raised  and  lip-like  than  the  other  portions,  the  zooecia  towards  the  lateral 
margins  somewhat  more  elevated  than  those  towards  the  central  portion  of 
the  branches.  The  apertures  commonly  subquadrangular  and  a  little  broader 
in  a  transverse  direction,  with  a  slight  indentation  upon  the  side  opposite  the 
higher  portion  of  the  peristome;  in  some  examples  the  apertures  approach  a 
subcircular  outline.  The  larger  diameter  of  the  apertures  is  commonly  about 
.02  mm.  or  a  little  more,  and  the  spaces  between  the  apertures  is  somewhat 
greater  than  the  width  of  the  apertures  themselves. 

Remarks. — This  species  suggests  C.  pustulosa  in  some  respects,  but  the 
linear  arrangement  of  the  zooecia  is  less  distinct,  the  apertures  are  somewhat 
more  crowded,  and  the  most  elevated  side  of  the  peristomal  border  is  situated 
distally,  giving  the  apertures  the  appearance  of  being  directed  backwardly. 
In  C.  pustulosa  the  most  elevated  portion  of  the  peristome  is  lateral,  upon 
the  outer  side  in  each  case,  the  outer  apertures  appearing  to  be  directed  towards 
the  median  line  of  the  branches,  while  those  towards  the  center  have  the 
peristome  about  equally  elevated  all  around,  with  no  part  of  it  as  high  as 
the  outer  borders  of  the  marginal  zooecia. 

This  species  is  one  of  the  most  characteristic  forms  in  the  Lower  Chester 
faunas  in  Illinois.  It  occurs  abundantly  and  is  present  in  practically  every 
full  collection  from  the  Renault  and  Paint  Creek  formations  in  St.  Clair, 
Monroe,  and  Randolph  counties,  but  has  nowhere  been  observed  either  above 
or  below  these  horizons.  No  species  of  Cystodictya  whatever  has  been  recorded 
from  any  true  Ste.  Genevieve  limestone  fauna,  and  none  has  ever  been  de- 
tected by  the  writer.  In  southern  Illinois  the  species  occurs  commonly  in 
the  Shetlerville,  Renault,  and  Paint  Creek  formations,  and  it  is  present  in  the 
same  formations  in  Crittenden  County,  Kentucky.  The  species  constitutes 
one  of  the  many  strong  bonds  between  the  Renault  and  the  "Upper  Ohara." 

Example  of  a  species  of  Cystodictya  from  the  Chester  of  Caldwell  County, 
Kentucky,  are  preserved  in  the  Walker  Museum  at  the  University  of  Chicago, 
from  the  Bassler  collection.     These  specimens   are  of  this   common   Lower 


PALEONTOLOGY  351 

Chester  species,  and  are  recorded  under  the  name  of  C.  labiosa,  said  to  be  a 
manuscript  name  applied  by  Ulrich.  In  describing  the  species  in  this  place 
Ulrich's  manuscript  name  is  retained  in  order  that  no  confusion  in  nomen- 
clature may  be  introduced. 

Horizon  and  locality. — Shetlerville  formation,  Hardin  County,  Illinois, 
and  Crittenden  County,  Kentucky.  Eenault  limestone,  Monroe,  Randolph, 
and  Hardin  counties,  Illinois,  and  Crittenden  County,  Kentucky.  Paint 
Creek  formation,  St.  Clair,  Monroe,  Randolph,  Johnson,  and  Pope  counties, 
Illinois. 

GlYPTOPORA  PUNCTIPORA  Ulrich 

Plate  VII,  Fig.  25 
1890.     Glyptopora  punctipora  Ulrich,  Geol.  Surv.  111.,  vol.  8,  p.  519,  pi.  78, 
figs.  9-9a. 

This  bryozoan  is  a  rather  common  form  that  has  not  been  found  outside 
of  the  Lower  Chester  formations  in  Monroe  and  Randolph  counties,  Illinois, 
and  elsewhere.  The  specimen  figured  is  from  the  basal  Chester,  Shetlerville 
formation,  of  Crittenden  County,  Kentucky.  It  occurs  in  southeastern  Illi- 
nois in  the  same  formation  and  in  the  Renault. 

Horizon  and  locality. — Shetlerville  formation,  Hardin  County,  Illinois, 
and  Crittenden  County,  Kentucky.  Renault  formation,  Monroe,  Randolph, 
and  Hardin  counties,  Illinois.  Paint  Creek  formation,  Monroe,  Randolph, 
and  Johnson  counties,  Illinois. 

Rhipidomella  dubta  (Hall) 

Plate  VIII,  Figs.  5-6 
1856.     Orthis  dubia  Hall,  Trans.  Albany  Inst.,  vol.  4,  p.  12. 
1914.     Rhipidomella  dubia  Weller,  111.  State  Geol.  Surv.,  Monog.  I,  p.  160, 
pi.  20,  figs.  22-26,  pi.  83,  figs.  9-10. 

No  brachiopod  belonging  to  the  family  Orthidae  has  been  found  in  any 
Chester  fauna  in  Illinois,  but  Rhipidomella  dubia  occurs  rather  commonly  in 
the  Ste.  Genevieve  limestone,  and  in  every  preceding  fauna  down  to  the 
Keokuk  limestone. 

Horizon  and  locality. — Keokuk  limestone,  Warsaw  limestone,  Spergen 
limestone,  and  St.  Louis  limestone,  many  localities  in  Iowa,  Missouri,  and 
Illinois.  Ste.  Genevieve  limestone,  Ste.  Genevieve  County,  Missouri,  Union 
and  Hardin  counties,  Illinois. 

PUGNOIDES    OTTUMWA     (White) 

Plate  VIII,  Figs.  1-4 
1862.     Rhynchonella  Ottumwa  White,  Proc.  Bost.  Soc.  Nat.  Hist.,  vol.  9,  p. 
23. 


352  GEOLOGY    OF   HARDIN    COUNTY 

1914.  Pugnoides  ottumwa  Weller,  111.  State  Geol.  Surv.,  Monog.  I,  p.  193, 
pi.  25,  figs.  7-17. 

Rhynchonelloid  shells  are  unusual  in  those  Mississippian  formations 
that  are  represented  in  Hardin  County,  but  Pugnoides  ottumwa  can  usually 
be  discovered  if  prolonged  enough  search  is  made  for  it  in  the  Fredonia 
limestone.  It  is  one  of  the  very  best  index  fossils  of  the  Ste.  Genevieve,  and 
is  a  marker  of  this  horizon  from  Fort  Dodge,  Iowa,  to  central  Kentucky. 
It  has  never  been  observed  in  the  Chester,  and  the  only  rhynchonelloid  shell 
that  has  been  detected  in  the  Chester  of  Illinois  is  very  different  from  this 
one,  and  is  a  member  of  another  genus.  The  Pugnoides  ottumwa  zone  is  a 
well  defined  horizon  in  the  Mississippian,  and  all  the  evidence  that  has  been 
accumulated  goes  to  show  that  it  is  a  contemporaneous  horizon  throughout 
its  whole  geographic  extent. 

Horizon  and  locality. — Ste.  Genevieve  limestone,  numerous  localities  in 
Iowa,  near  Alton,  Illinois,  St.  Clair,  Monroe,  Randolph,  and  Union  counties, 
Illinois,  Ste.  Genevieve  County,  Missouri.  Fredonia  limestone,  Rosiclare, 
Illinois,  Cedar  Bluff,  near  Princeton,  Kentucky,  and  near  Bowling  Green, 
Kentucky. 

Spiriferina  subspinosa  n.  sp. 

Plate  VIII,  Figs.  7-14 

Description.— Shell  small,  wider  than  long,  the  hinge-line  a  little  shorter 
than  the  greatest  width  of  the  shell,  the  cardinal  extremities  rounded.  The 
dimensions  of  a  medium  sized  example  are :  length  from  front  to  umbo  of 
pedicle  valve  9  mm.,  length  of  brachial  valve  6.7  mm.,  greatest  width  10 
mm.,  length  of  hinge-line  8.5  mm.,  thickness  8  mm. 

Pedicle  valve  with  a  prominent  umbo,  the  surface  curving  abruptly  to 
the  cardinal  margin,  more  gently  to  the  anterior  margin,  not  compressed 
towards  the  cardinal  extremities;  mesial  sinus  sharply  defined,  moderately 
wide  and  rather  deep,  subangular  or  sharply  rounded  in  the  bottom,  extending 
to  the  beak;  the  beak  small,  pointed  and  incurved;  cardinal  area  moderately 
high,  concave,  the  curvature  increasing  towards  the  beak,  the  lateral  margins 
defined  but  interrupted  from  the  surfaces  of  the  lateral  slopes  by  a  slight 
ridge  only;  height  and  width  of  the  delthyrium  about  equal;  each  lateral 
slope  marked  by  from  four  to  six  subangular,  simple  plications  which  originate 
along  the  cardinal  margin,  those  bounding  the  mesial  sinus  are  the  strongest, 
the  others  being  successively  smaller  to  the  cardinal  extremities. 

Brachial  valve  less  convex  than  the  pedicle,  the  greatest  depth  near  the 
middle;  the  lateral  slopes  convex,  not  distinctly  compressed  towards  the 
cardinal  extremities;  mesial  fold  rounded  or  subangular,  sharply  defined, 
similar  to  the  plications  upon  the  lateral  slopes  but  somewhat  broader  and 
higher;  beak  small;  cardinal  area  very  narrow;  the  plications  on  the  lateral 
slopes  similar  to  those  of  the  opposite  valve  and  alternate  with  them. 


PALEONTOLOGY  353 

Surface  of  both  valves,  when  well  preserved,  marked  by  fine,  closely 
crowded,  evenly  distributed,  small  tubercles  or  papillae  which  exhibit  a 
tendency  to  be  arranged  in  radiating  rows.  A  number  of  concentric  lines  of 
growth  are  also  commonly  present  towards  the  front  of  the  shell.  Shell 
substance  coarsely  punctate. 

Remarks. — This  shell  is  allied  to  S.  spinosus  and  has  been  referred  to 
as  a  variety  of  that  species  by  some  authors.  The  shell  differs  constantly 
from  the  typical  S.  spinosa  in  its  smaller  size  and  much  more  rotund  form, 
also  in  the  smaller  number  of  plications  and  in  the  much  greater  fineness  of 
the  papillae  which  cover  the  surface.  These  constant  differences,  associated 
with  the  fact  that  the  two  forms  clo  not  occur  together,  but  are  characteristic 
of  distinct  horizons  in  the  Chester  series,  seem  to  be  sufficient  reason  for 
recognizing  this  form  as  a  distinct  species. 

The  size  of  the  shells  varies  considerably.  The  specimen  whose  dimen- 
sions "  have  been  given  is  larger  than  usual ;  but  the  largest  example  which 
has  been  observed  has  a  maximum  length  of  10.3  mm.,  and  width  of  11.5  mm. 
A  usual  length  for  the  shell  is  about  7  mm. 

Horizon  and  locality. — Sbetlerville  formation,  Hardin  and  Pope  counties, 
Illinois;  Crittenden  County,  Kentucky.  The  species  has  been  identified  in 
every  Shetlerville  fauna  that  has  been  collected  within  this  area. 

Spiriferina  transversa   (McChesney) 

Plate  VIII,  Figs.  17-18 
1860.     Spirifer  transversa  McChesney,  Desc.  New  Spec.  Foss.,  p.  42. 
1914.     Spiriferina   transversa  Weller,   111.    State   Geol.   Surv.,   Monog.   I,   p. 
297,  pi.  35,  figs.  41-49. 

Spiriferina  spinosa  (N.  &  P.) 

Plate  VIII,  Figs.  15-16 
1855.     Spirifer  spinosus  Norwood  and  Pratten,  Jour.  Acad.  Nat.  Sci.,  Phil., 

(2),  vol.  3,  p.  71,  pi.  9,  figs,  la-cl. 
1914.     Spiriferina  spinosa  Weller,  111.  State  Geol.  Surv.,  Monog.  I,  p.  299, 
pi.  35,  figs.  50-58. 
In  Monroe  and  Randolph  counties,  Illinois,  Spiriferina  transversa  is  the 
common  member  of  the  genus  in  the  Renault  formation,  while  S.  spinosa 
becomes  much  more  common  in  the   Paint   Creek.     Both  species,  however, 
occur  in  each  formation,  and  also  in  still  higher  formations  of  the  Chester. 
The  same  distributional  relationship  of  the  two  species  in  the  Lower  Chester 
is  observed  in  southeastern  Illinois,  S.  transversa  is  common  in  the  "Upper 
Ohara,"   being   especially   abundant   in   the    Shetlerville   formation,   and   S. 
spinosa  is  much  more  common  in  the  Paint  Creek.    While  this  evidence  alone 
—23  G 


354  GEOLOGY  OF  HARDIN  COUNTY 

would  have  but  little  weight  in  the  decision  of  a  'question  of  correlation,  yet 
in  association  with  the  mass  of  other  evidence  which  unites  the  "Upper 
Ohara"  with  the  typical  Kenault,  and  the  beds  between  the  Bethel  and  Cypress 
sandstones  with  the  Paint  Creek,  it  serves  to  strengthen  the  main  contention. 

Cliothyridina  sublamellosa   (Hall) 

Plate  VIII,  Figs.  21-24 
1858.     Athyris  sublamellosa  Hall,  Geol.  Iowa,  vol.  1,  pt.  2,  p.  702,  pi.  27, 

figs.  la-c. 
.1914.  Cliothyridina  sublamellosa  Weller,  111.  State  Geol.  Surv.,  Monog.  I, 
p.  482,  pi.  80,  figs.  31-36. 
This  is  one  of  the  very  common  species  in  the  Lower  Chester  formations, 
although  it  is  not  limited  to  these  horizons.  It  is  a  long  range  species,  being 
present  in  the  Ste.  Genevieve  limestone  below,  and  in  the  Middle  Chester 
above. 

Composita  trinuclea   (Hall) 

Plate  VIII,  Figs.  19-20 
1856.     Terebratula  trinuclea  Hall,  Trans.  Albany  Inst.,  vol.  4,  p.  7. 
1914.     Composita  trinuclea  Weller,  111.  State  Geol.  Surv.,  Monog.  I,  p.  486, 
pi.  81,  figs.  16-45. 

The  genus  Composita  is  present  in  practicallv  every  Mississippian  fauna, 
and  in  many  horizons  it  is  one  of  the  commonest  forms.  If  is  one  of  those 
genera  in  which  the  species  exhibit  very  great  variation,  and  after  studying 
large  collections  the  observer  is  always  at  a  loss  to  know  whether  he  should 
lump  all  together  from  all  horizons  in  a  single  protean  species,  or  to  separate 
them  into  innumerable,  more  limited  specific  groups.  As  a  rule  the  specimens 
from  one  horizon  with  a  limited  geographic  range,  are  fairly  well  circum- 
scribed in  their  characters,  at  least  the  individuals  in  such  a  group  vary 
less  among  themselves  than  the  group  as  a  whole  differs  from  some)  other 
group  from  another  horizon  or  locality.  However,  it  is  always  possible  to 
find  numerous  examples  which  are  intermediate  in  character  between  any 
of  the  groups  that  may  be  recognized. 

In  the  Chester,  the  examples  of  Composita  found  in  the  Lower  and 
Middle  divisions  of  the  group  are  notably  different  from  those  in  the  Upper 
division.  The  earlier  type  is  commonly  smaller  and  more  elongate  in  out- 
line, the  higher  one  being  large  and  broad,  and  more  or  less  subquadrate  in 
outline.  The  earlier  form  is  not  notably  different  from  specimens  which 
may  be  found  in  the  underlying  Ste.  Genevieve,  St.  Louis,  and  Spergen 
faunas,  and  all  are  here  referred  to  the  species  C.  trinuclea. 


PALEONTOLOGY  355 

GOLCONDA  AND  LOWER  OKAW  SPECIES 

Pentremites  obesus  Lyon 

Plate  X,  Figs.  1-3 
1851.     Pentremites  obesus  Lyon,  Rep.  Ky.  Geol.  Snrv.,  vol.  3,  p.  469,  pi.  2, 

figs.  1-ld. 
1905.  Pentremites  obesus  Ulrich,  U.  S.  Geol.  Snrv.,  Prof.  Paper,  No.  36, 
p.  64,  pi.  7,  figs.  1-4. 
This  is  the  largest  species  of  Pentremites  in  the  Chester  faunas  of 
Illinois,  and  is  perhaps  the  largest  known  member  of  the  genus.  It  is  highly 
characteristic  of  the  basal  portion  of  the  Golconda  limestone,  and  at  this 
time  it  has  not  been  found  in  any  other  position.  No  specimens  of  the  species 
have  yet  been  collected  in  Hardin  County,  but  they  may  be  looked  for  in  the 
outcrops  of  the  lower  portion  of  the  Golconda  limestone  in  the  county. 

Horizon    and    locality. — Lower   part   of   the    Golconda    limestone,    Pope 
County,  Illinois,  and  Crittenden  County,  Kentucky. 

Pentremites  platybasis  n.  sp. 

Plate  IV,  Figs.  37-42 
Description. — Body  of  medium  size  or  smaller,  wider  than  high  in  the 
typical  form,  the  greatest  width  at  or  near  the  lower  extremity  of  the  am- 
bulacra. The  dimensions  of  the  holotype,  a  nearly  perfect  specimen,  are: 
height  12.8  mm.,  greatest  width  13.5  mm.,  length  of  ambulacra  11.9  mm., 
greatest  width  of  ambulacra  4.1  mm.  Dorsal  region  of  the  body  nearly  flat, 
the  surface  extended  into  five  shoulders  reaching  to  the  lower  ends  of  the 
ambulacra,  the  spaces  between  very  gently  concave  towards  the  outer  margin 
and  curving  uninterruptedly  into  the  interambulacral  areas  of  the  ventral 
region;  the  basal  plates  reaching  about  half  way  from  the  stem  facet  to  the 
lower  extremities  of  the  ambulacra,  marked  at  their  center  by  a  low,  triangu- 
lar callosity  the  points  of  which  are  directed  along  the  three  basal  sutures, 
the  stem  facet  in  the  center  of  this  callosity;  the  base  slightly  indented 
radially  along  the  three  basal  sutures,  the  indentation  along  the  suture  be- 
tween the  two  larger  basal  plates  being  somewhat  stronger  than  the  others. 
Ventral  region  of  the  body,  from  the  extremities  of  the  ambulacra  to  the 
summit,  with  converging  sides,  the  profile  being  gently  convex  with  the  con- 
vexity increasing  somewhat  above,  the  summit  truncated.  Ambulacra  nearly 
flat  at  their  lower  extremities,  becoming  very  broadly  V-shaped  towards  the 
summit,  each  of  the  two  lateral  surfaces  gently  convex  below,  becoming 
essentially  flat  above ;  the  lateral  grooves  ten  to  twelve  in  the  space  of  3  mm., 
directed  transversely  at  the  summit,  becoming  oblique  towards  the  extremities 
of  the  ambulacra  with  their  inner  ends  curving  slightly  in  a  ventral  direction. 
Interambulacral   areas    nearly   flat   transversely,   with   the   margins    slightly 


356  GEOLOGY  OF  HARDIN  COUNTY 

elevated,  the  marginal  elevation  becoming  a  little  greater  ventrally.  The 
deltoid  plates  less  than  one-half  the  length  of  the  ambulacra,  their  dorsal 
margins  straight  and  meeting  at  the  median  line  in  an  angle  greater  than 
90°. 

Remarks. — This  species  is  perhaps  a  successor  of  P.  godoni,  in  the  Okaw 
and  Golconda  limestones.  In  its  typical  form  it  differs  from  the  earlier 
species  in  its  flatter  base  and  in  the  shallow  Y-shaped  cross-section  of  the 
ambulacra  towards  the  summit.  The  lateral  furrows  of  the  ambulacra  are 
also  a  little  finer  than  in  P.  godoni.  Like  all  species  of  this  genus,  this  one 
exhibits  a  considerable  range  of  variation,  the  most  noticeable  variable  char- 
acters being  the  flatness  of  the  base  and  the  depth  of  the  V-shaped  ambulacral 
groove.  Some  specimens  which  are  associated  with  typical  examples  and  are 
connected  with  them  by  all  intermediate  variations  are  higher  than  they  are 
wide  and  have  a  base  that  is  less  flat,  in  some  cases  the  profile  of  the  base 
being  not  unlike  that  of  P.  godoni,  The  characters  of  the  ambulacra  are 
constantly  different  from  P.  godoni,  but  their  depth  towards  the  summit 
exhibits  considerable  variation. 

Horizon  and  locality. — Lower  Okaw  limestone,  Randolph  and  St.  Clair 
counties,  Illinois;  Lower  Golconda  limestone,  Pope  and  Hardin  counties, 
Illinois. 

Pentremites  nodosus  Hambach 

Plate  IV,  Fig.  25 
1880.  Pentremites  nodosus  Hambach,  Trans.  St.  Louis  Acad.  Sci.,  vol.  4, 
p.  155,  pi.  B,  fig.  2. 
Description. — Body  of  medium  size  or  larger,  higher  than  wide,  the 
greatest  width  at  the  extremities  of  the  ambulacra,  the  dorsal  and  ventral 
regions  subequal  in  height.  The  dimensions  of  a  nearly  perfect  specimen  are : 
height  27  mm.,  greatest  width  22.7  mm.,  length  of  ambulacra  17.9  mm., 
greatest  width  of  ambulacra  5.4  mm.,  distance  from  stem  facet  to  ends  of 
ambulacra  17  mm.  Dorsal  region  obpyramidal  in  form,  the  lines  separating 
the  surfaces  of  the  pyramid  well-defined  towards  the  ambulacral  extremities, 
becoming  obsolete  towards  the  base,  the  profile  of  the  dorsum  is  concavely 
curved  above,  becoming  straight  or  even  a  little  convex  as  it  approaches  the 
stem  facet;  transversely  the  surfaces  are  concave  between  the  ambulacral 
extremities;  on  three  sides,  determined  by  the  sutures  between  the  basal 
plates,  there  are  somewhat  flattened  surfaces  towards  the  base  of  the  dorsum, 
so  that  the  pentagonal  cross  section  at  the  plane  separating  the  dorsum  and 
the  ventral  regions,  becomes  somewhat  triangular  towards  the  base;  the  basal 
plates  reaching  about  one-half  or  a  little  less  than  one-half  the  distance  from 
the  stem  facet  to  the  bases  of  the  ambulacra.  Ventral  region  subhemispherical 
or  subhemiellipsoidal  in  form.     The  ambulacra  with  a  rather  broad  median 


PALEONTOLOGY  357 

groove,  each  of  the  two  lateral  surfaces  nearly  symmetrically  depressed  convex 
transversely,  in  some  examples  with  the  slope  to  the  median  groove  a  little 
more  abrupt,  these  two  surfaces  together  forming  a  nearly  flat  ambulacra! 
surface  which  may  be  gently  convex;  or  sloping  inward  to  the  median 
groove  to  form  a  very  wide  and  shallow  V-shaped  cross-section.  The  side 
plates  eight  to  ten  in  number  in  the  space  of  3  mm. ;  the  lateral  grooves 
nearly  straight  and  transverse  towards  the  summit,  becoming  somewhat 
oblique  distally.  The  interambulacral  regions  distinctly  concave  in  a 
transverse  direction  in  their  outer  portion;  in  the  upper  portions,  including 
the  deltoid  plates  and  the  extremities  of  the  radials,  they  are  more  nearly 
flat,  especially  in  older  individuals.  The  lateral  margins  of  the  interam- 
bulacral regions  somewhat  raised  and  roughened,  this  roughened  region 
narrow  towards  the  extremities  of  the  ambulacra,  but  broader  above  and  con- 
nected entirely  across  the  areas  with  an  arch-like  outline  below  the  deltoid 
plates,  and  from  this  position  towards  the  summit  occupying  much  of  the 
area  of  the  deltoid  plates.  This  roughness  of  the  plates  most  pronounced 
about  opposite  the  lower  extremities  of  the  deltoid  plate  giving  rise  to  the 
thickening  of  the  radial  plates  which  doubtless  suggested  the  specific  name 
of  the  form.  The  deltoid  plates  rather  small,  subrhomboidal  in  form,  the 
two  free  margins  commonly  a  little  longer  than  the  others,  the  sutures  between 
the  deltoids  and  the  radials  straight  in  the  median  region,  but  curving  out- 
ward as  they  approach  the  margins. 

Remarks. — The  roughness  or  callous  development  upon  the  interam- 
bulacral regions  of  this  species,  which  has  given  origin  to  its  specific  name, 
is  a  character  that  is  somewhat  inconstant,  being  nearly  obsolete  upon  some 
individuals.  It  is  quite  likely  that  the  feature  increases  in  prominence  with 
the  age  of  the  individuals,  and  that  younger  specimens  may  be  quite  free 
from  it. 

Horizon  and  locality. — Lower  Okaw  limestone  (lower  part),  Randolph 
County,  Illinois. 

Pentremites  okawensis  n.  sp. 

Plate,  X,  Figs.  5-7 
Description: — Body  of  medium  size,  much  higher  than  wide,  the  greatest 
width  at  the  extremities  of  the  ambulacra,  the  ventral  region  shorter  than 
the  dorsal.  The  dimensions  of  the  holotype  are:  height  25.3  mm.,  greatest 
width  15.7  mm.,  length  of  ambulacra  12.5  mm.,  greatest  width  of  ambulacra 
5  mm.,  distance  from  the  stem  facet  to  the  extremities  of  the  ambulacra  16 
mm.  The  dorsal  region  obpyramidal  in  form,  with  the  lines  separating  the 
faces  of  the  pyramid  well  defined  towards  the  ends  of  the  ambulacra  but 
becoming  nearly  or  quite  obsolete  towards  the  stem  facet;  the  profile  of  the 
dorsum  with  straight  or  nearly  straight  sides  through  the  greater  portion  of 


358  GEOLOGY    OF    HARDIN    COUNTY 

their  length,  but  becoming  a  little  concave  towards  the  basal  extremities  in 
many  specimens;  the  surfaces  of  the  dorsum  flat  transversely  towards  the 
line  separating  the  dorsal  and  ventral  regions,  longitudinally  these  surfaces 
curve  without  interruption  into  the  interambulacral  regions  of  the  ventral 
region;  the  basal  plates  reaching  less  than  one-half  the  distance  from  the 
stem  facet  to  the  ambulacra.  Ventral  region  having  the  sides  converging 
with  a  gently  convex  curvature  to  the  truncate  summit.  The  ambulacra  very 
slightly  convex  or  nearly  flat  transversely,  with  the  median  groove  well 
defined,  each  of  the  two  lateral  surfaces  unsymmetrically  depressed  convex, 
the  inner  margins  curving  rather  abruptly  to  the  median  groove,  much  the 
larger  portion  of  the  surfaces  essentially  flat  or  with  the  extreme  outer  border 
having  a  slight  downward  curvature;  the  side  plates  seven  to  nine  in  number 
in  the  space  of  3  mm.,  the  transverse  grooves  nearly  straight  and  horizontal 
near  the  summit,  becoming  oblique  towards  the  extremities  of  the  ambulacra. 
The  interambulacral  regions  flat  transversely,  the  lateral  margins  only 
slightly  elevated  towards  the  extremities  of  the  deltoid  plates.  The  deltoid 
plates  small,  their  tips  not  extending  to  the  summit. 

Remarks. — In  its  flat  interambulacral  surfaces,  both  in  the  dorsal  and 
ventral  regions,  and  in  its  small  and  short  deltoid  plates,  this  species  re- 
sembles P.  pyramidatus.  It  differs  from  that  species  in  its  more  elongate  and 
consequently  narrower  form,  with  the  elongation  more  marked  in  the  dorsal 
than  in  the  ventral  region,  the  distance  from  the  stem  facet  to  the  bases  of  the 
ambulacra  being  greater  than  the  length  of  the  ambulacra.  In  the  collections 
that  have  come  under  the  observations  of  the  writer,  P.  pyramidatus  is  more 
commonly  met  with  in  the  Paint  Creek  faunas,  while  this  species  occurs 
commonly  in  the  Middle  Chester  faunas,  both  in  the  Mississippi  Valley  region 
and  in  the  Ohio  Valley. 

Horizon  and  locality. — Okaw  limestone,  Eandolph  County,  Illinois.  Gol- 
conda  limestone,  Pope  and  Hardin  counties,  Illinois.  Glen  Dean  limestone, 
Hardin  County,  Illinois. 

Mesoblastus  incurvatus  n.  sp. 

Plate  VIII,  Figs.  29-34 
Description. — Body  small,  pentangularly  subglobose  in  form,  height  and 
width  subequal  or  the  height  a  little  greater  than  the  width,  the  base  im- 
pressed a  little  within  the  distal  extremities  of  the  ambulacra.  The  dimen- 
sions of  a  nearly  undistorted  specimen  are :  height  7  mm.,  width  7  mm.,  width 
of  ambulacra  1  mm.  The  largest  specimen  observed,  a  distorted  example  is 
approximately  10  mm.  in  height.  Ambulacra  very  narrow,  the  median  groove 
rather  faint  distally,  becoming  more  pronounced  towards  the  oral  extremity 
where  it  is  nearly  equal  in  strength  to  the  lateral  grooves  which  border  the 
ambulacra,  giving  to  the  proximal  third  or  fourth  a  three  grooved  appearance ; 


PALEONTOLOGY  359 

the  lancet  plate  nearly  or  wholly  covered  by  the  side  plates  distally,  its  central 
portion  exposed  proximally  by  the  shortening  of  the  side  plates;  side  plates 
between  30  and  35  in  number,  broader  distally,  becoming  narrower  towards 
the  summit  and  consequently  the  lateral  pores  of  the  ambulacra  become  much 
more  crowded  proximally.  Interambulacral  spaces  gently  concave  trans- 
versely, becoming  rather  deeply  concave  between  the  distal  extremities  of  the 
ambulacra;  the  deltoid  plates  about  one-fourth  the  length  of  the  body,  the 
base  of  the  plates  obtusely  angular,  the  apex  acutely  angular,  the  entire  plate 
being  unsymmetrically  rhomboidal  in  outline;  the  lateral  margins  of  the 
interambulacral  spaces  becoming  progressively  more  elevated  above  the  am- 
bulacra towards  the  summit  of  the  body.  Plates  nearly  smooth,  marked  only 
by  indistinct  lines  of  growth  parallel  with  the  base  of  the  deltoid  plates. 

Remarks. — Two  other  species  of  the  genus  Mesoblastus  have  been  de- 
scribed from  the  Chester  faunas,  ill.  glaber  and  M.  sphaeroidalis.  The  first 
of  these  is  a  common  species  in  the  Shetlerville  formation  and  many  ex- 
amples have  been  collected  at  Fairview  bluff  below  Eosiclare  and  elsewhere. 
ill.  incurvatus  differs  from  M.  glaber  in  its  larger  size,  being  on  the  average 
at  least  twice  as  large  as  the  Shetlerville  species,  by  the  greater  incurving  of 
the  distal  extremities  of  the  ambulacra,  the  tips  of  these  areas  being  relatively 
much  closer  to  the  stem  facet;  the  stem  facet  is  more  deeply  impressed  be- 
tween the  tips  of  the  ambulacra ;  the  deltoid  plates  differ  in  shape,  the  sutures 
between  the  tips  of  the  forked  plates  and  the  deltoids  being  essentially  straight 
and  diverging  at  an  angle  a  little  greater  than  a  right  angle,  while  in  iH. 
glaber  these  two  sutures  are  in  more  nearly  a  straight  horizontal  line  and 
are  curved,  the  base  of  the  deltoid  plate  being  a  double  curve  with  the  con- 
vexity towards  the  oral  extremity  of  the  body ;  the  plates  of  ill" .  incurvatus  are 
smoother,  especially  in  the  region  near  the  junction  of  the  forked  plates  with 
the  deltoids,  than  in  ill.  glaber. 

The  specific  name  of  ill.  glaber  is  a  misnomer.  The  type  specimens 
are  nearly  smooth,  but  they  are  apparently  somewhat  worn  examples.  Per- 
fectly fresh,  unworn  specimens  from  the  Shetlerville  shales  at  Fairview 
bluff  commonly  show  distinct,  ridge-like  lines  of  growth  upon  the  deltoid 
plates  and  upon  the  distal  portions  of  the  forked  plates,  the  more  distinctly 
marked  of  these  lines  being  parallel  with  the  basal  sutures  of  the  deltoid 
plates.     Both  of  the  other  species  are  really  smoother  than  ill.  glaber. 

M.  sphaeroidalis  is  less  well  known  than  M.  glaber,  the  single  type  speci- 
men from  Meade  County,  Kentucky,  being  the  only  one  observed  by  the 
writer,  is  labeled  Kaskaskia  group,  so  its  proper  position  in  the  Chester  is 
not  recorded.  In  size  and  in  the  shape  of  the  deltoid  plates  this  species 
resembles  ill.  incurvatus,  but  in  general  form  and  proportions,  and  in  the  less 
incurvature  of  the  extremities  of  the  ambulacra,  it  is  more  like  ill.  glabra. 

Horizon  and  locality. — Golconda  limestone,  NE.  V4  sec.  28,  T.  12  S..  E. 
7  E.,  Pope  County,  Illinois. 


360  GEOLOGY    OF    HARDIN    COUNTY 

Pterotocrinus  capitalis   (Lyon) 

Plate  VIII,  Figs.  36-39 
1875.     Asterocrinus  capitalis  Lyon,  Geol.  Rep.  Ky.,  vol.  3,  p.  472,  pi.  5,  figs. 

la-Ik. 
1897.     Pterotocrinus    capitalis   Wachsmuth   and    Springer,   X.    Amer.    Crin. 
Cam.,  p.  794,  pi.  79,  figs.  6a-b. 

This  species  is  the  genotype  of  Pterotocrinus,  a  genus  of  crinoids  which 
is  characterized  by  the  development  of  a  remarkable  series  of  five  plates, 
interradial  in  position,  growing  out  from  the  ventral  surface.  These  special- 
ized plates,  commonly  referred  to  as  the  "wing  plates/5  exhibit  a  great  variety 
of  forms,  and  the  species  are  differentiated  largely  upon  the  characteristics 
of  these  plates.  Complete  specimens  of  members  of  the  genus  are  rarely  met 
with,  and  even  specimens  of  the  dorsal  cups  are  rare,  the  parts  usually  found 
being  the  separated  "wing  plates."  In  P.  capitalis  these  plates  are  much 
more  massive  than  in  any  of  the  other  known  species  of  the  genus,  their  form 
being  well  exhibited  by  the  illustrations  shown  on  Plate  VIII.  This  is  per- 
haps the  best  index  fossil  of  the  lower  portion  of  the  Golconda  limestone,  but 
it  has  not  yet  been  observed  in  the  equivalent  part  of  the  Okaw  limestone  of 
Randolph  County. 

Horizon  and  locality. — Golconda  limestone,  Johnson,  Pope,  and  Hardin 
counties,  Illinois,  Crittenden  County,  Kentucky. 

Camarophoria  explanata  (McChesney) 

Plate  IX,  Figs.  35-36 
1860.     Rhynchonella  explanata  McChesney,  Desc.  New  Pal.  Foss.,  p.  50. 
1914.     Camarophoria  explanata  Weller,  111.  State  Geol.  Surv.,  Monog.  I,  p. 
173,  pi.  23,  figs.  46-51. 
So  far  as  is  known  this  species  makes  its  first  appearance  in  the  Chester 
faunas  of  Illinois  in  the  Okaw  and  Golconda  limestones,  which  are  equivalent 
formations.     Not  a  single  example  has  yet  come  to  the  notice  of  the  writer 
from  the  Lower  Chester  formations,  but  it  does  continue  upwards  into  the 
higher  formations  of  the  group.     Scarcely  a  Middle  Chester  fauna  will  be  met 
with  in  which  the  species  is  wanting,  and  in  many  places  it  is  one  of  the 
common  species. 

Cliotpiyridina  sublamellosa  (Hall) 

PJate  IX,  Figs.  39-41 

Examples  of  this  species  occur  in  great  numbers  in  the  Golconda  and 

Glen  Dean,  wherever  these  formations  are  well  exposed.     They  are  especially 

abundant  in  some  localities  in  the  lower  portion  of  the  Golconda  limestone. 

The  Middle  Chester  examples  are  not  notably  different  from  those  found  in 


PALEONTOLOGY  361 

the  Lower  Chester,  unless  it  be  in  the  slightly  coarser  divisions  of  the  con- 
centric, lamellar  expansions  of  the  shell. 

COMPOSITA    TRINUCLEA    (Hall) 

Plate  IX,  Figs.  37-38 
The  examples  of  Composita  found  in  the  Middle  Chester  faunas  are  not 
essentially  different  from  those  in  the  Lower  Chester  which  have  already  been 
noticed.  The  species  occurs  in  abundance  in  the  Golconda  and  Glen  Dean 
faunas  in  Hardin  County  and  elsewhere,  wherever  these  formations  are  well 
exposed. 

XtTCULA   PLATYNOTUS   n.   sp. 

Plate  IX,  Figs.  11-14 

Description. — Shell  small,  subtrigonal  in  outline,  with  very  deep  valves. 
The  dimensions  of  the  holotype,  a  complete  specimen  with  valves  in  articula- 
tion are:  length  11.1  mm.,  height  9.2  mm.,  thickness  9.3  mm.  Beaks  promi- 
nent, strongly  incurved,  situated  nearly  opposite  the  anterior  margin,  but 
not  quite  terminal.  Anterior  margin  a  little  concave  above,  just  in  front  of 
the  beaks,  becoming  gently  convex  below  and  rounding  without  interruption 
into  the  ventral  margin  which  is  gently  convex  or  nearly  straight  in  its  central 
portion,  curving  upward  more  abruptly  in  front  and  behind;  postero-ventral 
margin  short,  narrowly  rounded;  postero-dorsal  margin  long,  nearly  straight 
or  gently  concave,  becoming  a  little  convex  as  it  approaches  the  beaks. 
Valves  very  convex,  flattened  on  the  umbo,  with  prominent,  narrowly  rounded 
umbonal  ridge  passing  from  the  beaks  to  the  postero-basal  margin;  post- 
umbonal  slope  very  abrupt,  these  slopes  of  the  two  valves  when  in  articulation, 
forming  a  broad,  nearly  flat,  postero-dorsal  region,  becoming  concave  towards 
the  beaks  and  slightly  keeled  along  its  median  line  posteriorly,  where  the 
cardinal  margins  of  the  two  valves  join.  The  antero- ventral  slope  flattened 
longitudinally  for  some  distance  in  front  of  the  umbonal  ridge,  with  a  very 
shallow,  ill-defined  sinus  passing  obliquely  from  the  beak  to  near  the  middle 
of  the  ventral  margin,  strongly  convex  vertically,  rounding  abruptly  to  the 
antero-dorsal  margin  in  front  of  the  beak.  Surface  of  valves  marked  by  fine, 
continuous,  concentric  costae  somewhat  variable  in  size,  becoming  less  regular 
towards  the  ventral  margin  in  mature  shells.  An  incomplete  internal  cast 
shows  a  pair  of  strong  posterior  adductor  muscular  impressions  and  well- 
defined  foot  muscle  scars,  and  taxodont  hinge  tooth  impressions. 

Remarks. — This  is  a  unique  type  of  pelecypod  shell  in  the  Chester  faunas, 
or  in  the  faunas  of  any  of  the  Mississipian  formations  of  the  Mississippi 
Valley.  In  its  general  form  it  is  suggestive  of  some  species  of  Schizodus,  but 
it  is  a  thicker  shell  than  is  usual  in  that  genus,  and  moreover  it  possesses  a 
taxodont  hinge  dentition  which,  so  far  as  its  characters  have  been  determined, 


362  GEOLOGY    OF    HARDIN    COUNTY 

corresponds  with  the  dentition  in  Nucula.  The  species  has  been  placed  in 
the  genus  Nucula  entirely  upon  the  evidence  afforded  by  the  hinge  characters. 

The  first  specimens  of  this  shell  that  came  under  observation  were  col- 
lected from  near  the  base  of  the  Okaw  limestone  on  Camp  Creek  in  Randolph 
County,  Illinois.  Later,  the  species  was  collected  from  near  the  base  of  the 
Golconda  limestone  in  Johnson  County,  where  it  has  been  found  to  be  more 
abundant  and  in  general  somewhat  better  preserved  than  in  Eandolph  County. 
The  mature  examples  from  Johnson  County  attain  a  somewhat  larger  size 
than  any  of  the  Camp  Creek  specimens,  but  this  difference  in  size  is  not  a 
constant  character,  and  all  are  certainly  members  of  the  same  species. 

Horizon  and  locality. — 'Basal  Okaw  limestone,  Camp  Creek,  Randolph 
County,  Illinois;  and  basal  Golconda  limestone,  3%  miles  southeast  of 
Vienna,  Johnson  County,  Illinois. 

Nucula  randolphensis  n.  sp. 

Plate  IX,  Figs.  24-30 

Description. — Shell  of  medium  size,  subovate  in  outline.  The  dimen- 
sions of  two  mature  examples  with  the  valves  in  articulation  are:  length  11 
mm.  and  10.8  mm.,  height  9.7  mm.,  and  9.9  mm.,  thickness  7.5  mm.  and  7.5 
mm.  The  beaks  strongly  incurved,  those  of  the  two  valves  nearly  in  contact, 
situated  from  a  fourth  to  a  third  of  the  shell  length  from  the  anterior  ex- 
tremity, the  umbonal  region  very  prominent  in  mature  shells.  The  antero- 
dorsal  margin  sloping  more  or  less  abruptly  from  in  front  of  the  beaks,  in 
some  examples  passing  without  interruption  to  the  most  anterior  point  of 
the  shell  margin,  in  others  with  the  margin  just  above  the  anteriormost  point 
of  the  shell  slightly  truncate;  the  ventral  margin  convexly  curved  through- 
out, passing  without  interruption  into  the  postero-ventral  margin  which  is 
somewhat  broadly  rounded ;  the  postero-dorsal  margin  gently  convex  or  nearly 
straight,  sloping  backward  from  behind  the  beaks.  The  valves  strongly  con- 
vex, the  antero-dorsal  and  postero-dorsal  portions  curving  somewhat  abruptly 
to  the  margins,  becoming  distinctly  incurved  in  front  of,  and  especially  for 
a  short  distance  back  from  the  beaks,  the  region  back  of  the  beaks  forming 
a  broad,  ill-defined  escutcheon;  the  lunule  in  front  of  the  beaks  less  well 
defined  than  the  escutcheon.  The  surface  of  the  valves  marked  by  fine, 
regular,  concentric  costae,  and  in  some  examples  by  one  or  more  stronger 
lines  of  growth.  The  shell  substance  thick,  with  deeply  impressed  muscle 
scars;  the  internal  casts  of  the  shell  more  pointed  posteriorly  than  the  shell 
itself. 

Remarks. — This  species  differs  from  Nucula  illinoie?isis  in  its  larger 
size,  and  its  proportionally  lesser  length.  On  comparison  of  young  examples 
of  N.  randolphensis  with  mature  individuals  of  N.  illinoiensis  of  equal  size, 
the  valves  of  N.  randolphensis  are  much  less  convex  so  that  the  shells  are 


PALEONTOLOGY  363 

very  much  thinner,  but  with  growth  to  maturity  the  shells  of  the  larger 
species  become  as  obese  as  those  of  the  smaller  form.  Perfect  examples  of 
this  species  exhibit  considerable  variation  in  the  outline  of  the  shell,  especially 
in  the  truncation  of  the  antero-dorsal  margin,  and  in  the  sharpness  of  the 
rounding  of  the  posterior  extremity. 

Horizon  and  locality. — Basal  Okaw  limestone,  Camp  Creek,  Eandolph 
County,  Illinois;  and  basal  Golconda  limestone,  3%  miles  southeast  of 
Vienna,  Johnson  County,  Illinois. 

Leda  chesteeexsis  n.  sp. 

Plate  IX,  Figs.  31-34 

Description. — Shell  large  for  the  genus,  subovate  in  outline,  contracted 
posteriorly.  The  dimensions  of  a  practically  perfect  right  valve  are:  length 
22  mm.,  height  13.4  mm.,  convexity  5  mm.  A  larger  individual  has  a  height 
of  18.8  mm.,  but  it  is  worn  at  the  posterior  extremity  so  its  length  cannot  be 
determined  accurately.  The  beaks  are  directed  posteriorly,  situated  near  the 
mid-length  of  the  shell.  The  antero-dorsal  margin  gently  convex,  with  the 
greatest  convexity  just  in  front  of  the  beaks,  passing  without  interruption 
into  the  rounded  anterior  margin;  the  ventral  margin  convexly  curved,  the 
curvature  a  little  more  abrupt  in  some  examples  at  a  point  nearly  opposite 
the  beaks,  becoming  straighter  both  in  front  and  back  of  this  point ;  posterior 
margin  very  short,  abruptly  rounded  below  and  subtruncate  above,  rounding 
abruptly  into  the  ventral  and  dorsal  margins;  postero-dorsal  margin  con- 
cave, the  greatest  concavity  commonly  just  back  of  the  beaks.  Valves  strongly 
convex,  the  greatest  convexity  along  a  vertical  line  through  the  beaks;  along 
a  straight  or  slightly  curved  line  from  the  beak  to  a  point  near  the  center 
of  the  ventral  margin,  the  regular  convex  curvature  of  the  surface  of  the 
shell  in  an  antero-posterior  direction,  is  interrupted  by  a  slightly  more  abrupt 
curvature,  which  gives  the  appearance  of  a  low,  ill-defined,  rounded  fold 
crossing  the  valves  in  a  nearly  vertical  direction,  in  some  shells  this  fold 
becomes  obsolete  towards  the  ventral  margin,  but  in  others  it  continues 
entirely  across  the  valve.  Along  the  antero-dorsal  margin  the  shell  surface 
is  incurved  to  the  hinge  margin;  postero-dorsally  the  surface  is  abruptly 
inflected  to  form  a  broad,  flattened  escutcheon  which  is  distinctly  depressed 
behind  the  beaks.  Surface  of  valves  marked  by  fine,  regular,  concentric 
costae,  five  or  six  of  which  commonly  occupy  the  space  of  one  millimeter  on 
the  body  of  the  shell,  becoming  finer  towards  the  beak. 

Remarks. — This  species  is  of  the  type  of  Leda  nasuta  Hall,  from  the 
Spergen  limestone,  and  Leda  curia  M.  and  W.,  from  the  Ste.  Genevieve  lime- 
stone, but  it  attains  a  very  much  greater  size  than  either  of  these  species,  and 
it  is   distinguished   also  by  the   indefinite   vertical   fold  which   crosses   each 


364  GEOLOGY   OF    HARDIN    COUNTY 

valve.     Very  young  specimens  agree  with  the  older  species  more  closely  than 
do  the  mature  shells,  the  mature  individuals  being  perfectly  distinct. 

Horizon  and  locality. — Basal  Okaw  limestone,  Camp  Creek,  Randolph 
County,  Illinois;  and  basal  Golconda  limestone,  3%  miles  southeast  of 
Vienna,  Johnson  County,  Illinois. 

CONOCARDIUM    CHESTERENSIS    n.    Sp. 

Plate  IX,  Figs.  21-23 

Description. — Shell  small,  the  dimensions  of  the  largest  example  ob- 
served are:  height  along  an  oblique  line  from  the  beak  to  the  ventral  margin 
10.7  mm.,  length  along  an  oblique  line  from  the  anterior  extremity  of  the 
hinge-line  to  the  postero-basal  extremity  14  mm.  Beak  situated  near  the 
mid-length  of  the  shell,  only  a  little  produced  beyond  the  hinge-line.  The 
antero-cardinal  extremity  of  the  shell  acutely  angular;  the  antero-ventral 
margin  nearly  straight  or  very  gently  convex;  the  postero-ventral  margin 
rounded  and  bending  abruptly  into  the  posterior  margin  which  is  obliquely 
truncate;  the  postero-cardinal  extremity  not  noticeably  produced  beyond  the 
shell  margin.  Valves  with  their  greatest  convexity  along  an  oblique  band 
extending  from  the  beak  to  the  rounded  postero-basal  margin,  this  band  gently 
convex  antero-posteriorly,  and  strongly  convex  dorso-ventrally.  In  front  of 
the  median  band  the  surface  sloping  away  without  interruption  into  the  trian- 
gular anterior  portion  of  the  valve  which  becomes  compressed  towards  the 
anterior  extremity  and  incurved  rather  abruptly  to  the  hinge-margin. 
The  posterior  slope  of  the  valves  from  the  median  band  much  more  abrupt 
than  the  anterior,  and  nearly  flat  throughout  the  greater  portion  of  its  width, 
becoming  a  little  deflected  close  to  the  cardinal  line.  Surface  of  the  valves 
marked  by  radiating  costae,  about  five,  in  some  cases  six  of  the  stronger  ones 
occupying  the  oblique  median  band  of  the  valve;  the  anterior  slope  with  from 
twenty  to  thirty  or  more  costae,  according  to  the  size  of  the  shell,  which  are 
much  finer  than  those  upon  the  median  band;  the  costae  upon  the  posterior 
slope  ten  or  twelve  in  number,  and  these  likewise  much  finer  than  those 
of  the  median  band;  the  strongest  rib  of  the  entire  valve  is  the  one  along 
the  posterior  border  of  the  median  band.  In  addition  to  the  radiating  ribs, 
the  shell  surface  is  marked  by  very  fine,  raised,  concentric  lines  which  are 
well-defined  in  the  intercostal  spaces,  and  obsolete  on  the  tops  of  the  radiating 
costae,  also  in  most  examples  several  concentric  lines  of  growth  are  present. 

Rmarks. — This  form  is  allied  to  C.  mesialis  from  the  Ste.  Genevieve 
limestone,  but  it  differs  from  that  species  in  the  less  abrupt  differentiation 
of  the  mesial,  band  from  the  anterior  slope  of  the  valve,  and  in  the  absence 
of  a  posterior  prolongation  of  the  shell  at  the  cardinal  margin.  It  is  possible 
that  the  postero-cardinal  portion  of  the  shell  was  really  somewhat  more  pro- 
duced in  living  shells  than  seems  to  be  the  case  in  the  fossil  specimens  that 


PALEONTOLOGY 


365 


have  been  examined,  all  of  which  have  been  more  or  less  worn,  but  in  none  of 
these  is  there  any  indication  of  the  shell  outline  itself,  or  in  the  direction  of 
the  lines  of  growth,  that  they  ever  possessed  such  an  extension  as  is  present 
in  the  type  of  0.  mesialis. 

Horizon  and  locality. — Basal  Okaw  limestone,  Camp  Creek,  Eandolph 
County,  Illinois ;  and  basal  Golconda  limestone,  3y2  miles  southeast  of  Vienna, 
Johnson  County,  Illinois. 

Bellerophon  chesterensis  n.  sp. 

Plate  IX,  Figs.  1-6 

Description. — Shell  of  medium  size,  snbglobose,  closely  coiled,  without 
umbilicus,  the  length  and  width  about  equal.  The  dimensions  of  an  essen- 
tially complete  example  are:  greatest  length  20  mm.,  greatest  width  across 
the  aperture  20  mm.,  length  of  aperture  at  its  mid-width  7  mm.  Outer 
volution  broadly  rounded  dorsally,  becoming  somewhat  flattened  in  mature 
shells  towards  the  aperture;  center  of  dorsum  marked  by  a  narrow,  elevated 
band,  rounded  over  the  top.  Aperture  transverse,  twice  as  wide  as  high,  with 
a  deep  slit  dorsally  opposite  the  dorsal  band;  the  inner  lip  callosed,  the  cal- 
losity extending  over  the  umbilical  region  in  mature  shells.  Surface  of  the 
shell  marked  only  by  more  or  less  regular  lines  of  growth  which  are  much 
more  conspicuous  towards  the  aperture  of  the  larger  shells. 

Remarks. — This  species  resembles  B.  sublaevis  from  the  Spergen  lime- 
stone, but  the  shell  is  proportionally  broader,  and  more  flattened  on  the 
dorsum,  with  more  prominent  dorsal  band,  and  commonly  with  more  con- 
spicuous lines  of  growth. 

Horizon  and  locality. — Basal  Okaw  limestone,  Camp  Creek,  Eandolph 
County,  Illinois;  and  basal  Golconda  limestone,  3%  miles  southeast  of 
Vienna,  Johnson  County,  Illinois. 

EUPHEMUS    RANDOLPHENSIS    n.    Sp. 

Plate  IX,  Figs.  7-10 
Description. — Shell  small,  subglobose,  closely  coiled,  without  umbilicus. 
The  dimensions  of  a  nearly  complete  but  rather  small  example  are:  greatest 
length  10  mm.,  greatest  width  across  the  aperture  8.6  mm.,  length  of  aperture 
at  its  middle  line  3  mm.  One  of  the  largest  examples  observed  has  a  maxi- 
mum length  of  about  15  mm.  Outer  volution  with  a  more  or  less  distinctly 
rounded  ridge  medially,  from  which  the  surface  slopes  laterally,  becoming 
more  convex  a  little  beyond  the  middle  of  each  side  and  curving  somewhat 
abruptly  into  the  umbilical  region.  Aperture  transverse,  with  a  broadly 
rounded  sinus  in  the  outer  margin  opposite  the  dorsal  ridge;  the  dorsal  band 
rather  broad,  rounded  transversely,  not  sharply  defined  laterally.     Surface 


366  GEOLOGY    OF    HARDIN    COUNTY 

marked  by  fine,  regular,  raised,  revolving  costae  which  are  narrower  than  the 
intercostal  spaces,  and  which  terminate  abruptly  at  about  the  middle  of  the 
outer  volution;  the  outer  half  of  the  volution  nearly  smooth  or  marked  only 
by  more  or  less  inconspicuous  lines  of  growth.  In  some  examples  there  is  a 
more  or  less  prominent,  rounded  node  upon  each  lateral  slope  of  the  outer 
volution  at  about  the  position  of  the  termination  of  the  revolving  costae,  and 
in  these  same  specimens  the  dorsal  ridge  is  commonly  somewhat  more  promi- 
nent than  in  others,  giving  to  the  shell  a  somewhat  trilobate  form  in  that 
portion  of  the  volution. 

Remarks. — The  presence  of  Bellerophontid  shells,  even  as  rare  indi- 
viduals, in  the  Chester  faunas  of  the  Mississippi  and  Ohio  valleys  is  unusual, 
and  no  species  of  Euphemus  has  ever  been  described  from  the  faunas,  although 
Girty  has  reported  the  genus  from  the  Batesville  sandstone  of  Arkansas.  The 
occurrence  of  a  species  of  Euphemus,  therefore,  in  the  Okaw  limestone  on 
Camp  Creek,  represented  literally  by  scores  of  finely  preserved  individuals,  is 
a  remarkable  faunal  character.  Besides  this  form  the  same  fauna  includes 
a  number  of  other  Bellerophontid  shells  belonging  to  at  least  two  different 
genera,  some  of  which  are  fairly  common.  This  group  of  species  gives  to 
the  Camp  Creek  fauna  a  very  unusual  character  for  the  Chester.  The  same 
species  of  Euphemus,  along  with  at  least  two  of  the  other  bellerophontid  species 
from  Camp  Creek,  occur  also  at  one  locality  in  the  lower  Golconda  limestone 
in  Johnson  County.  The  species  is  fully  as  abundant  in  the  Johnson  County 
locality  as  on  Camp  Creek,  and  the  specimens  from  the  two  localities  are  alike 
in  all  essential  characters.  There  are  also  other  notable  characteristics  that 
unite  the  faunas  from  the  two  localities. 

This  species  resembles  the  Pennsylvanian  Euphemus  carbonarius,  but  it 
is  somewhat  less  globular  in  form,  with  less  strong  revolving  costae,  and  in 
most  examples  with  more  prominent  dorsal  ridge  upon  the  outer  volution. 

Horizon  mid  locality. — Basal  Okaw  limestone,  Camp  Creek,  Randolph 
County,  Illinois;  and  basal  Golconda  limestone,  3%  miles  southeast  of 
Vienna,  Johnson  County,  Illinois. 

BUCANOPSIS   ORNATUS   11.   Sp. 

Plate  IX,  Figs.  15-20 
Description. — Shell  of  medium  size,  with  small  umbilicus.  The  dimen- 
sions of  the  holotype  are:  greatest  length  21  mm.,  greatest  width  across  the 
aperture  21.1  mm.,  length  of  aperture  at  its  mid-width,  approximately  11 
mm.  Outer  volution  rather  narrow  where  it  leaves  the  inner  margin  of  the 
aperture,  expanding  regularly  from  this  position  until  it  approaches  the 
aperture  where  it  is  distinctly  flaring,  its  surface  rather  narrowly  rounded 
across  the  median  line,  the  sides  convex  and  curving  rather  abruptly  into  the 
umbilicus.     Dorsal  band   of  medium   width,   elevated  above  the   surface   on 


PALEONTOLOGY  367 

either  side,  rounded  transversely,  becoming  much  more  strongly  elevated 
towards  the  aperture.  The  aperture  about  twice  as  wide  as  long,  with  a  deep 
mesial  slit  in  its  outer  lip,  the  inner  lip  with  a  thin  callosity.  Surface  marked 
by  very  fine  revolving  costae,  irregularly  alternating  in  size  or  nearly  uniform 
from  five  to  nine  occupying  the  space  of  one  millimeter ;  crossing  the  revolving 
costae  there  are  equally  fine  but  somewhat  fainter,  transverse  markings,  the 
two  sets  of  lines  producing  an  exceedingly  fine  reticulate  ornamentation;  the 
dorsal  band  marked  by  longitudinal  and  transverse  lines  similar  to  those 
on  the  body  of  the  shell.  In  addition  to  the  finer  markings,  the  larger  shells 
especially,  are  marked  by  more  or  less  conspicuous  lines  of  growth,  which  in 
some  examples  obscure  the  finer  markings. 

Remarks. — This  species  is  found  associated  with  Euphemus  randolphensis 
in  both  Randolph  and  Johnson  counties.  In  the  Johnson  County  locality 
it  is  the  largest  and  one  of  the  commonest  Bellerophontid  shells,  but  not 
nearly  so  abundant  as  Euphemus  randolpliensis.  In  the  Camp  Creek  locality 
in  Randolph  County,  only  a  single  example  has  been  met  with,  and  while  it  is 
somewhat  imperfect,  it  is  clearly  the  same  species  as  that  from  Johnson 
County.  Several  of  the  larger  shells  of  the  species  show  evidence  of  having 
been  injured  during  their  growth,  the  healed  lines  of  growth  being  very 
evident,  a  condition  that  is  perhaps  indicative  of  the  thinness  of  the  shells. 
The  surface  markings  of  the  shell  suggest  B.  textilis  from  the  Spergen  lime- 
stone, but  this  Chester  species  is  very  much  larger  and  has  a  more  flaring- 
aperture. 

Horizon  and  locality. — Basal  Okaw  limestone,  Camp  Creek,  Randolph 
County,  Illinois;  and  basal  Golconda  limestone,  3%  miles  southeast  of 
Vienna,  Johnson  County,  Illinois. 


3G8  GEOLOGY    OF    HARDIN    COUNTY 

MISCELLANEOUS  CHESTEE  SPECIES 

Pentremites  spicatus  Ulrich 

Plate  X,  Fig.  8 
1918.     Pentremites  spicatus  Ulrich,  Ky.  Geol.  Surv.,  Miss.  Form.  West  Ky., 
p.  262,  pi.  7,  figs.  33-35.     (Name  and  illustrations  published  with- 
out description.) 

Description. — Body  large,  deeply  pentalobate,  the  ventral  region  much 
higher  than  the  dorsal,  the  greatest  width  at  or  a  little  above  the  distal  ex- 
tremities of  the  ambulacra.  The  dimensions  of  a  nearly  perfect  specimen 
are:  height  37.9  mm.,  greatest  width  33.1  mm.,  length  of  the  ambulacra  31.5 
mm.,  distance  from  the  center  of  the  stem  facet  to  the  distal  extremities  of 
the  ambulacra  19.2  mm.  Dorsal  region  with  a  concave  profile  from  the  distal 
extremities  of  the  ambulacra  to  the  stem  facet,  the  surfaces  extending  out- 
ward to  the  ambulacra  in  the  form  of  five  conspicuous  shoulders,  the  inter- 
ambulacral  spaces  becoming  deeply  concave  towards  the  outer  border.  Ventral 
region  having  sides  with  a  gently  convex  profile,  converging  towards  the 
summit.  The  ambulacra  broad,  and  deeply  Y-shaped  transversely,  each  of 
the  two  sides  flat  or  slightly  concave  towards  the  summit,  becoming  less 
concave  or  slightly  convex  distally;  a  narrow  lateral  border  on  each  side,  in 
which  are  situated  the  lateral  pores,  slightly  incurved  to  the  lateral  surfaces 
of  the  radial  and  deltoid  plates.  Side  plates  eight  to  ten  in  the  space  of  3 
mm.,  the  lateral  grooves  transverse  throughout  most  of  the  ambulacra,  be- 
coming slightly  oblique  distally.  Interambulacral  areas  deeply  concave  below, 
becoming  shallower  above;  a  rather  broad  band  along  the  lateral  borders 
differentiated  from  the  central  region  and  more  or  less  distinctly  marked 
by  oblique  irregularities  which  in  some  cases  give  a  serrate  margin  to  the 
plates.  The  deltoid  plates,  Avhen  uninjured,  extending  conspicuously  above 
the  summit  in  five  points. 

Remarks. — This  is  the  species  that  has  been  referred  commonly  by 
authors  to  P.  sidcatus,  a  species  which,  as  shown  in  Boemer's  original  illus- 
tration, does  not  possess  the  projecting  deltoid  plates  which  are  so  character- 
istic of  P.  spicatus.  The  species  occurs  abundantly  in  the  Glen  Dean  lime- 
stone in  many  localities,  from  Eandolph  County,  Illinois,  to  Breckenridge 
County,  Kentucky,  and  it  seems  to  be  limited  to  this  horizon,  but  it  has  not 
yet  been  met  with  in  Hardin  County. 

Horizon  and  locality. — Upper  Okaw  limestone  (Plum  Creek  beds), 
Eandolph  County,  Illinois.  Glen  Dean  limestone,  Pope  County,  Illinois,  and 
Crittenden  and  Breckenridge  counties,  Kentucky. 


PALEONTOLOGY  369 

Pentremites  brevis  III  rich 

Plate  IV,  Figs.  43-46 
1918.     Pentremites  brevis  Ulrich,  Butts,  Ky.  Geol.  Surv.,  Miss.  Form.  West. 

Ky.,  p.  100,  pi.  24,  fig.   6.      (Named  and  illustrated  but  without 

published  description.) 
Description. — Body  of  medium  size,  almost  as  wide  as  high  or  a  little 
higher  than  wide,  the  greatest  width  at  the  lower  extremities  of  the  ambu- 
lacra. The  dimensions  of  a  practically  perfect  individual  are:  height  17.7 
mm.,  greatest  width  17.3  mm.,  length  of  ambulacra  15.8  mm.,  greatest  width 
of  ambulacra  5.4  mm.  Dorsal  region  of  the  body  depressed  to  a  somewhat 
variable  degree,  in  some  examples  nearly  flat ;  the  stem  facet  nearly  flush  with 
the  general  surface,  or  slightly  depressed  with  three,  radiating,  depressed 
lines  extending  outward  along  the  basal  sutures,  situated  in  the  center  of  a 
trifoliate  callosity,  the  lobes  of  which  reach  out  along  the  basal  sutures ;  the 
ambulacral  regions  of  the  dorsal  surface  a  little  prominent  towards  the  lower 
extremities  of  the  ambulacra,  the  interambulacral  surfaces  flat  or  gently 
concave  transversely,  curving  regularly  into  the  interambulacral  surfaces  of 
the  ventral  region.  Ventral  region  of  the  body,  from  the  lower  extremities 
of  the  ambulacra  to  the  summit,  with  gently  convex  sides  converging  towards 
the  summit,  which  is  subtruncate.  Ambulacra  broadly  V-shaped,  the  median 
depression  extending  to  the. lower  extremities  of  the  areas  but  increasing  in 
depth  towards  the  summit,  each  of  the  two  lateral  surfaces  nearly  flat  or  very 
gently  convex  towards  the  outer  margins  and  flattened  towards  the  median 
line;  the  lateral  grooves  nine  to  thirteen  in  the  space  of  three  millimeters, 
directed  obliquely  inward  and  upward  in  the  lower  portion  of  the  ambulacra, 
becoming  transverse  towards  the  summit.  Interambulacral  areas  nearly  flat 
transversely,  becoming  slightly  concave  below  in  some  examples,  the  lateral 
margins  very  slightly  elevated  as  they  approach  the  summit.  The  deltoid 
plates  less  than  one-half  the  length  of  the  ambulacra,  the  dorsal  margins 
gently  convex  and  meeting  at  the  median  line  in  an  angle  less  than  90°. 

Remarks. — This  species  is  most  closely  related  to  P.  platybasis  which 
occurs  commonly  near  the  base  of  the  Okaw  limestone  and  in  the  lower 
portion  of  the  Golconda  limestone.  The  general  form  of  the  two  species  is 
essentially  alike,  and  the  callosity  upon  which  the  stem  facet  is  situated  is 
similar  in  the  two  species.  The  only  really  important  difference  between 
the  two  forms  is  found  in  the  depth  of  the  V-shaped  ambulacral  surfaces,  this 
depression  being  much  deeper  in  P.  brevis  than  in  P.  platybasis.  The  deep- 
ening of  the  V-shaped  groove  is  apparently  a  progressive  character,  in  P. 
godoni  of  the  Paint  Creek  formation  the  ambulacral  surfaces  are  flat  or 
slightly  convex;  in  the  lower  Okaw  and  Golconda  limestone  species,  P.  platy- 
habis,  it  is  somewhat  V-shaped ;  while  in  the  species  under  consideration  from 
the  Glen  and  Upper  Okaw  limestones,  it  is  much  depressed. 
—24  G 


370  GEOLOGY    OF   HARDIN    COUNTY 

The  specimens  that  are  here  illustrated  are  from  the  Upper  Okaw  Plum 
Creek  beds  of  Randolph  County.  Typical  examples  of  the  species  are  present 
in  the  Glen  Dean  formation  of  Hardin  County,  but  no  Hardin  County 
examples  have  been  met  with  which  are  as  large  as  some  of  those  from 
Randolph  County. 

Horizon  and  locality. — Upper  Okaw,  Plum  Creek  beds,  Randolph 
County,  Illinois;  Glen  Dean  limestone,  Hardin  County,  Illinois. 

Penteemites  fohsi  Ulrich 

Plate  X,  Fig.  4 
1905.     Pentremites  fohsi  Ulrich,  U.  S.  Geol.  Surv.,  Prof.  Paper  No.  36,  p. 
64,   pi.   7,  figs.   5-9.      (Name   and   illustrations  published  without 
description.) 

Description. — Body  large,  higher  than  wide,  the  greatest  width  at  the 
distal  extremities  of  the  ambulacra.  The  dimensions  of  an  average  sized 
individual  are :  height  38.8  mm.,  greatest  width  30.4  mm.,  length  of  ambu- 
lacra 28.2  mm.,  distance  from  center  of  stem  facet  to  base  of  ambulacra  22.3 
mm.  Dorsal  region  of  the  body  obpyramidal  with  the  edges  between  the  faces 
of  the  pyramid  fairly  well  defined  towards  the  extremities  of  the  ambulacra, 
but  becoming  obsolete  towards  the  base;  the  basal  plates  covering  about  one- 
half  or  less  than  one-half  the  distance  from  the  stem  facet  to  the  ends  of  the 
ambulacra.  Ventral  region  somewhat  higher  than  the  dorsal,  the  surfaces 
converging  upward  with  a  gently  convex  curvature,  truncate  at  the  summit. 
Greatest  width  of  the  ambulacra  about  one-fourth  of  their  length,  the  two 
lateral  surfaces  sloping  inward  to  the  median  groove,  making  the  ambulacra 
broadly  V-shaped  in  cross-section,  each  of  the  lateral  surfaces  nearly  flat  in 
their  widest  portion  towards  the  summit,  becoming  gently  convex  in  the 
narrower,  distal  portion.  Side  plates  from  eight  to  ten  in  number  in  a 
distance  of  3  mm.,  the  lateral  grooves  nearly  transverse  in  direction  towards 
the  summit,  becoming  a  little  oblique  towards  the  distal  extremities  of  the 
ambulacra.  The  interambulacral  areas  nearly  flat  transversely,  their  lateral 
margins  very  slightly  or  not  at  all  raised  above  the  general  surface.  Deltoid 
plates  about  two-fifths  the  length  of  the  ambulacra,  their  upper  extremities 
not  extended  beyond  the  summit  ventrallty,  their  dorsal  margins  nearly  or 
quite  straight,  meeting  on  the  median  line  in  an  angle  of  less  than  90°. 

Remarks. — This  species  may  be  recognized  by  its  large  size,  although  it 
is  considerably  smaller  than  P.  obesus,  by  its  essentially  flat  interambulacral 
areas,  and  the  V-shaped  cross-sections  of  the  ambulacra. 

When  this  name  was  originally  proposed  by  Ulrich  the  species  was 
assigned  to  the  "Birdsville"  formation,  which,  of  course,  means  but  little  in 
our  present  interpretation  of  the  Chester.  Butts  has  copied  one  of  the 
original  figures1  and  has  assigned  the  species  to  the  Glen  Dean  formation. 

1Ky.  Geol.   Surv.,   Miss.   Form.  West.   Ky.,  pi.   24,  fig.   21. 


PALEONTOLOGY  371 

The  specimen  which  is  illustrated  in  this  report  is  from  the  Menard  lime- 
stone, and  the  species  has  not  been  found  by  the  writer  in  any  other  formation. 
It  occurs  throughout  southern  Illinois  from  Union  to  Pope  counties  in  a 
restricted  horizon  near  the  base  of  the  Menard  limestone  only  a  short  distance 
above  the  Waltersburg  sandstone,  and  it  has  been  found  in  this  zone  wherever 
the  formation  is  well  enough  exposed  to  permit  of  collecting  the  fossils. 

Horizon  and  locality.- — Menard  limestone,  Union,  Johnson,  and  Pope 
counties,  Illinois. 

Pentremites  cherokeeus  Hall 

Plate  X,  Figs.  11-13 
1858.     Pentremites  cherokeeus  Hall,  Geol.  Surv.  Iowa,  vol.  1,  pt.  2,  p.  691, 
pi.  24,  figs.  12a-c. 

Description. — Body  of  medium  size,  higher  than  wide,  the  greatest  width 
at  the  distal  extremities  of  the  ambulacra.  The  dimensions  of  a  nearly  com- 
plete specimen  are :  height  14.2  mm.,  greatest  width  13.8  mm.,  length  of 
ambulacra  10.7  mm.,  distance  from  center  of  stem  facet  to  distal  end  of  the 
ambulacra  7.9  mm.  Dorsal  region  broadly  obpyramidal,  the  five  faces  of  the 
pyramid  scarcely  defined  near  the  base,  but  becoming  depressed  and  distinctly 
concave  transversely  as  they  approach  the  line  separating  the  dorsal  and 
ventral  regions,  those  portions  of  the  dorsum  beneath  the  extremities  of  the 
ambulacra  forming  five  shoulder-like  regions;  the  basal  plates  reaching  about 
one-half  the  distance  from  the  stem  facet  to  the  extremities  of  the  ambulacra. 
Ventral  region  having  the  sides  converging  towards  the  summit  with  a 
gently  convex  curvature,  but  with  the  surfaces  a  little  recurved  in  the  inter- 
ambulacral  regions  towards  the  tips  of  the  deltoid  plates  when  these  plates 
are  uninjured;  the  summit,  when  the  tips  of  the  deltoid  plates  are  disre- 
garded, is  truncate.  The  ambulacra!  areas  broad,  their  width  from  two-fifths 
to  nearly  one-half  their  length,  broadly  V-shaped  in  cross-section  above, 
becoming  nearly  flat  towards  the  distal  extremities,  each  of  the  two  lateral 
surfaces  nearly  flat.  Side  plates  nine  to  eleven  in  the  space  of  3  mm.  Inter- 
ambulacral  areas  rather  deeply  concave  transversely  below,  becoming  flatter 
above  towards  the  extremities  of  the  deltoid  plates;  their  lateral  margins 
slightly  differentiated  along  a  narrow  band  adjacent  to  the  ambulacra  which 
is  marked  in  some  examples  with  more  or  less  obscure,  oblique  irregularities. 
The  deltoid  plates,  when  perfectly  preserved,  are  extended  conspicuously  above 
the  general  level  of  the  summit  in  five,  thin,  delicate  points  which  are  dis- 
tinctly recurved  towards  their  extremities. 

Remarks. — Hall  used  the  name  cherokeeus  for  a  species  of  Pentremites 
which  he  described  and  illustrated  in  his  Iowa  report  in  1858.  The  name  was 
taken  from  Troost's  manuscript,  but  the  specimen  used  for  description  and 
illustration  was  not  Troost's  type  of  the  species.     In  the  recently  published 


372  GEOLOGY    OP   HARDIN    COUNTY 

summary  of  Troost's  early  work1  an  illustration  is  given  of  the  specimen 
which  Troost  had  selected  as  the  type  of  his  species,  and  it  is  quite  clearly 
the  form  to  which  Ulrich  has  recently  given  the  name  P.  spicatus.  Hall's 
specimen  seems  to  be  distinct,  and  the  name  P.  cherokeeus  must  stand  or  fall 
upon  Hair's  interpretation. 

The  specimens  that  are  here  referred  to  the  species  have  been  collected 
at  a  number  of  localities  in  the  Menard  limestone  in  Randolph  and  Johnson 
counties,  and  have  been  found  in  no  other  horizon.  The  larger  of  these  is  a 
little  smaller  than  the  specimen  that  Hall  has  illustrated,  but  in  other  re- 
spects the  agreement  is  comparatively  close.  The  deltoid  plates  in  Hall's 
figures  are  somewhat  shorter  and  are  not  produced  above  the  summit  into 
the  delicate  points  of  the  specimens  under  discussion,  but  these  may  easily 
have  been  broken  off,  and  the  illustration  does  show  the  beginning  of  the 
recurvature  of  the  deltoid  plates  towards  the  tip.  Most  of  the  recently 
collected  specimens  are  in  about  the  condition  of  the  example  figured  by 
Hall.  Under  the  circumstances  it  seems  to  be  unwise  to  propose  a  new  name 
for  this  form,  although  a  careful  study  of  Hall's  type  may  make  such  a 
procedure  necessary. 

Horizon  and  locality. — Menard  limestone,  Randolph  and  Johnson  coun- 
ties, Illinois. 

Pterotocrinus  bifurcatus  Wetherby 

Plate  X,  Fig.  14 
1879.     Pterotocrinus  bifurcatus  Wetherby,  Jour.  Cinn.  Soc.  Nat.  Hist.,  vol. 

2,  p.  136,  pi.  11,  fig.  1. 
1897.     Pterotocrinus  acutus   var.    bifurcatus   Wachsmuth   and    Springer,   N. 

Amer.  Crin.  Cam.,  p.  801.  pi.  79,  figs.  9a-b. 
This  is  one  of  the  most  peculiar  species  of  this  peculiar  genus.  The 
"wing  plates"  which  exhibit  the  most  important  differential  characters  of 
the  several  species,  are  thick  and  heavy,  and  are  divided  distal ly  into  two 
widely  spreading,  horn-like  processes.  The  extent  of  these  horns  shows  a 
considerable  amount  of  variation  in  the  different  specimens  of  the  species,  but 
this  feature  in  some  degree  of  development  seems  to  be  constant.  The  speci- 
men illustrated  on  Plate  VII  is  the  original  type  specimen,  and  shows  the 
five  "wing  plates"  in  place,  from  above.  The  species  has  been  observed  only 
in  the  upper  or  Plum  Creek  beds  of  the  Okaw  limestone  in  the  Mississippi 
Valley  counties,  and  in  the  Glen  Dean  limestone  of  the  Ohio  Valley.  It  has 
not  yet  been  observed  in  Hardin  County,  but  it  may  be  looked  for. 

Horizon  and  locality. — Upper  Okaw  (Plum  Creek  beds),  Randolph 
County,  Illinois.     Glen  Dean  limestone,  Breckenridge  County,  Kentucky. 

'Wood.   Bull.   U.  S.   Nat.  Mus.,  No.   64. 


PALEONTOLOGY  373 

Pterotocrinus  menardensis  n.  sp. 

Plate  XI,  Fig.  9 

Description. — The  "wing  plates"  only  of  this  species  are  known.  These 
plates  are  large,  thin,  and  subovate  in  outline,  the  margin,  except  where  the 
plate  is  attached,  being  compressed  to  a  knife-like  edge.  The  upper  margin 
of  the  plate  is  regularly  arcuate  in  outline,  the  lower  margin  being  somewhat 
pointed.  The  dimensions  of  the  holotype,  which  is  a  very  perfect  plate,  are: 
greatest  width  vertically  28.2  mm.,  greatest  width  horizontally  24.3  mm., 
length  of  surface  of  attachment  14.2  mm.,  greatest  thickness  3  mm. 

Remarks. — The  "wing  plates"  of  this  species  more  nearly  resemble  those 
of  P.  depressus  than  any  other  of  the  described  species,  in  both  species  the 
plates  being  thin  and  widely  expanded.  Those  of  P.  menardensis  are  much 
the  larger  and  have  little  or  no  constriction  towards  the  area  of  attachment. 
These  plates  have  been  found  to  be  abundant  and  highly  characteristic  of 
the  same  zone  in  the  Menard  limestone  of  the  southern  counties  of  Illinois 
to  which  Pentremites  fohsi  seems  to  be  restricted.  Associated  with  these 
forms  there  are  numerous  bryozoans  and  some  brachiopods,  and  commonly, 
many  detached,  spinose,  crown  plates  of  a  species  of  Hydreionocrinus.  Neither 
this  species  nor  the  assemblage  of  which  it  is  a  member,  has  yet  been  observed 
in  the  Menard  limestone  of  Eandolph  County. 

Horizon  and  locality. — Menard  limestone,  Union,  Johnson,  Pope,  and 
Hardin  counties,  Illinois. 

Batostomella  nitidula  Ulrich 

Plate  XI,  Fig.  11 
1890.     Batostomella  nitidula  Ulrich,  Geol.  Surv.  111.,  vol.  8,  p.  436,  pi.  75, 
figs.  3-3b. 

This  bryozoan  occurs  in  abundance  in  some  localities  in  the  lower  part 
of  the  Clore  formation.  It  is  characterized  by  its  small,  delicate,  sub- 
cylindrical  branches,  which  are  commonly  much  broken.  In  general  the  species 
of  this  genus  require  thin  sections  for  examination  under  the  microscope,  for 
satisfactory  determination,  but  experience  has  shown  that  the  common  form 
in  the  lower  Clore  is  B.  nitidula,  and  little  hesitation  may  be  felt  in  so 
identifying  examples  from  this  horizon. 

Horizon  and  locality. — Clore  limestone,  Randolph,  Union,  Johnson, 
Pope,  and  Hardin  counties,  Illinois. 

Prismopora  serrulata  Ulrich 

Plate  XI,  Figs.  5-8 
1884.     Prismopora  serrulata  Ulrich,  Jour.  Cinn.   Soc.  Nat.  Hist.,  vol.  7,  p. 
41,  pi.  2,  figs.  2-2f. 
This   bryozoan   is  one   of  the  most  easily   recognized  members   of  this 
class  of  fossils.    The  triangular  cross-section  of  the  branches  is  different  from 


374  GEOLOGY    OF    HARDIN    COUNTY 

any  other  bryozoan  found  in  the  Chester  faunas  of  Illinois,  and  the  species  is 
characterized  by  the  regular  scallops  on  the  three  thin  margins  of  the 
branches.  The  species  is  the  best  index  fossil  of  the  Glen  Dean  limestone 
and  of  the  equivalent  horizon  in  Randolph  County,  but  it  is  not  wholly  re- 
stricted to  this  zone.  During  the  entire  time  that  has  been  devoted  to  the 
study  of  the  Chester  of  southern  Illinois,  one  single  example  of  the  species 
has  been  observed  in  the  Golconda  limestone.  At  one  locality  a  number  of 
poorly  preserved  specimens  of  this  or  an  allied  species  have  been  collected  in 
the  Paint  Creek,  in  Pope  County.  Above  the  Glen  Dean  limestone  the  species 
has  been  observed  in  a  number  of  localities  in  the  Vienna  limestone,  a  forma- 
tion which  lies  between  the  Glen  Dean  and  Menard,  separated  from  each  by 
a  sandstone,  in  Pope,  Johnson,  and  perhaps  also  Union  counties.  Notwith- 
standing these  other  occurrences,  the  species  remains  one  of  the  most  reliable 
markers  of  the  Glen  Dean  limestone,  and  at  some  localities  in  the  formation 
there  are  veritable  "Prismopora  gardens"  exhibited  upon  the  exposed  surfaces 
of  the  limestone,  and  the  species  may  be  found  in  practically  every  exposure 
of  the  formation  having  any  extent,  if  careful  search  is  made,  and  it  not 
infrequently  is  found  in  very  limited  exposures. 

Horizon  and  locality. — Golconda  limestone  (very  rare),  Hardin  County, 
Illinois.  Glen  Dean  limestone,  Union,  Johnson,  Pope,  and  Hardin  counties, 
Illinois,  and  Breckenridge  County,  Kentucky.  Upper  Okaw  limestone  (Plum 
Creek  beds),  Randolph  County,  Illinois.  Vienna  limestone,  Pope  and  John- 
son counties. 

Spirifer  increbescens  Hall 

Plate  XI,  Fig.  10 
1858.     Spirifer  increbescens  Hall,  Geol.  Surv.  Iowa,  vol.  1,  pt.  2,  p.  706,  pi. 

27,  figs.  6a-i. 
1914.     Spirifer  increbescens  Weller,  111.  State  Geol.  Surv.,  Monog.  I,  p.  343, 

pi.  46,  figs.  1-12. 
The  typical  form  of  S.  increbescens  is  the  large,  rather  strongly  convex 
shell  that  is  commonly  met  with  in  the  Menard  and  Clore  limestones  of  the 
Chester  group.  A  smaller  shell  is  present  in  the  Middle  and  Lower  Chester 
faunas,  but  it  is  more  delicate  in  appearance  and  is  quite  distinct  from  this 
larger  form  of  the  Upper  Chester.  In  much  of  the  past  literature  the  name 
S.  increbescens  has  been  applied  to  all  of  these  shells  in  the  Chester  faunas, 
but  the  smaller  form  should  at  least  be  distinguished  as  a  distinct  variety  and 
perhaps  as  a  species.  Some  of  those  with  much-extended  hinge-line  may  be 
referred  to  S.  increbescens  var.  transversalis  Hall,  and  others  perhaps  to 
S.  pellaensis.  There  is  a  whole  series  of  Spirifers  of  this  general  type,  with 
representatives  present  in  all  of  the  faunas  from  the  early  Mississippian  to 
the  summit  of  the  series,  and  even  continuing  into  the  Pennsylvanian,  in 
which  it  is  difficult  to  draw  sharp  lines  of  specific  demarcation,  but  which  do 


PALEONTOLOGY  375 

have  distinct  stratigraphic  values,  and  to  one  who  is  familiar  with  all  of  these 
the  true  S.  increbescens  always  indicates  Upper  Chester. 

Horizon  and  locality. — Menard  and  Clore  limestones,  Randolph,  Union, 
Johnson,  Pope,  and  Hardin  counties,  Illinois. 

COMPOSITA   SUBQUADRATA    (Hall) 

Plate  XI,  Figs.  12-14 
1858.     Athyris  subquadrata  Hall,  Geol.  Iowa,  vol.  1,  pt.  2,  p.  703,  pi.  27,  figs. 

2a-d;  p.  708,  text  fig.  118. 
1914.     Composita  subquadrata  Weller,  111.   State  Geol.   Surv.,  Monog.  I,  p. 
489,  pi.  81,  figs.  1-15. 

This  species  of  Composita,  which  occurs  abundantly  in  the  Menard  and 
Clore  formations,  differs  from  the  common  form  in  the  Middle  and  Lower 
Chester,  which  has  been  referred  to  C.  trinuclea,  in  its  much  larger  size  and 
its  greater  proportional  breadth.  The  shells  exhibit  considerable  variation 
in  outline,  but  the  more  usual  form  is  that  shown  in  figures  12  and  13,  which 
are  distinctly  subquadrate  in  outline,  as  the  name  suggests.  The  mistake  has 
been  made  in  the  past  by  many  authors,  in  referring  all  Chester  Compositae 
to  this  species,  but  the  name  should  be  restricted  to  the  large  form  of  the 
Upper  Chester  faunas. 

Horizon  and  locality. — Menard  and  Clore  limestones,  Randolph,  Union, 
Johnson,  Pope,  and  Hardin  counties,  Illinois. 

SULCATOPINNA  MISSOURIENSIS    (Swallow) 

Plate  XI,  Figs.  1-2 
1863.     Pinna  Missouriensis  Swallow,  Trans.  St.  Louis  Acad.  Sci.,  vol.  2,  p.  97. 
1894.     Pinna  missouriensis  Keyes,  Mo.  Geol.  Surv.,  vol.  5,  p.  116. 

Description. — Shell  elongate-cuneate  in  outline,  gaping  behind.  The 
specimens  commonly  occur  in  an  incomplete  condition,  but  when  complete 
they  must  have  attained  a  length  of  at  least  15  cm.  at  maturity,  with  a  maxi- 
mum height  of  4  to  4.5  cm.  Beaks  terminally  situated.,  the  anterior  extremity 
acutely  angular;  dorsal  margin  straight,  ventral  margin  straight  anteriorly 
and  meeting  the  dorsal  margin  at  the  beak  in  an  angle  of  about  15  degrees; 
posteriorly  the  ventral  margin  curves  dorsally  in  a  gently  convex  curvature 
which  passes  without  interruption  into  the  posterior  margin,  the  convexity 
of  the  curve  increasing  gradually  as  it  approaches  the  dorsal  margin  which 
it  meets  in  an  acute  angle.  Towards  the  beak  the  convexity  of  each  valve 
nearly  semicircular  so  that  the  cross-section  of  the  anterior  portion  of  the 
shell  is  subcircular;  posteriorly  the  convexity  of  the  valves  relatively  a  little 
flattened,  the  cross-section  being  subelliptica]  but  with  the  shorter  ends  of  the 
ellipse  angular,  the  ventral  side  more  acutely  so  than  the  dorsal  because  of  the 
slight  flattening  or  in  some  cases  a  gentle  concavity  of  the  valves  in  that 


376  GEOLOGY   OF   HARDIN    COUNTY 

direction  posteriorly.  Along  the  dorsal  margin,  just  below  the  hinge-line,  a 
narrow,  rounded  groove  is  present,  extending  the  entire  length  of  the  shell 
in  examples  from  which  the  entire  shell  substance  has  been  removed,  this 
groove  probably  being  due  to  the  thickening  of  the  inner  surface  of  the 
valves  along  the  hinge-line.  The  presence  of  these  grooves  in  the  internal 
casts,  as  the  species  is  commonly  preserved,  gives  the  shell  the  appearance 
of  being  keeled  along  the  dorsal  margin. 

Surface  of  each  valve  marked  by  from  20  to  25  longitudinal  corrugations, 
some  of  which  may  divide  at  intervals.  Postero-ventrally  the  longitudinal 
corrugations  become  obsolete  and  the  concentric  growth  lines  become  more 
conspicuous.  These  growth  lines  continue  across  the  longitudinal  corruga- 
tions, but  are  subordinate  to  them  upon  the  body  of  the  shell. 

The  approximate  dimensions  of  an  incomplete  example  are:  length  160 
mm.  or  more,  maximum  height  about  40  mm.,  thickness  20  mm. 

Remarks. — This  species  is  a  common  one  in  the  Menard  limestone,  and 
has  not  been  collected  in  the  Okaw  of  Golconda  limestones,  but  it  has  been 
found  rarely  in  the  Vienna  and  Glen  Dean  limestones.  It  commonly  occurs 
standing  vertically  in  the  limestone,  beaks  downward,  the  position  in  which 
it  existed  during  life.  The  shell  itself  is  very  thin  and  delicate,  without 
articulating  processes,  and  could  never  have  been  preserved  in  so  complete 
a  condition  as  that  in  which  it  commonly  does  occur,  with  the  two  valves 
together,  had  it  been  disturbed  from  its  original  position. 

The  specific  determination  of  the  shell  has  been  attended  with  some 
difficulty.  Pinna  missouriensis  was  originally  described  by  Swallow  without 
illustrations,  and  was  said  to  be  "abundant  in  the  Ste.  Genevieve  limestone  of 
Missouri  and  Illinois."  Swallow's  definition  fits  the  Menard  limestone  speci- 
mens very  well,  but  the  shell  does  not  occur  in  the  Ste.  Genevieve  limestone, 
nor  has  it  been  collected  in  Missouri,  the  youngest  Chester  formation  in 
that  state  being  the  Okaw  limestone.  However,  one  of  the  localities  cited  by 
Shumard  for  the  Ste.  Genevieve  limestone,  in  his  original  definition  of  the 
formation,  was  the  Mississippi  River  bluff  below  the  mouth  of  Marys  River, 
in  Randolph  County,  Illinois,  where  the  only  limestones  exposed  are  the 
Menard  and  Clore  formations  of  the  Chester,  and  he  may  have  had  examples 
of  the  species  from  one  or  the  other  of  these  formations,  labeled  as  from  the 
Ste.  Genevieve  limestone,  which  might  have  been  used  by  Swallow  in  his 
definition  of  the  species.  The  original  type  of  the  species  has  been  entirely 
lost  sight  of.  It  seems  clear  that  Worthen  identified  this  species,  the  only  one 
known  in  the  Chester,  as  Pinna  missouriensis,  from  a  statement  in  his  de- 
scription of  Pinna  St.  Ludovici1,  which  he  compares  with  "P.  Missouriensis 
of  the  Chester  group." 

Because  of  the  well  developed  longitudinal  corrugations  of  the  shell,  this 
species  has  been  transferred  to  Hyatt's  genus  Sulcatopinna,     The  species  is 

1Geol.   Surv.   111.,  vol.   7,  p.   326. 


PALEONTOLOGY  377 

very  closely  related  to  Pinna  maxvillensis  Whitfield,  from  the  Maxville  lime- 
stone of  Ohio,  and  it  is  not  unlikely  that  the  two  species  are  identical. 
Another  allied  form  is  Pinna  arkansana  Weller,  from  the  Batesville  sand- 
stone, but  the  Arkansas  species  apparently  has  much  less  convex  valves  than 
missouriensis. 

Horizon  and  locality. — Clore  limestone,  Kandolph  County,  Illinois. 
Menard  limestone,  Eandolph,  Union,  Johnson,  Pope,  and  Hardin  counties, 
Illinois.  Vienna  limestone  (very  rare),  Pope  County,  Illinois.  Glen  Dean 
limestone  (very  rare),  Johnson  County,  Illinois. 

Allorisma  olavata  McChesney 

Plate  XI,  Figs.  3-4 
1860.     Allorisma  clavata  McChesney,  Desc.  New  Pal.  Foss.,  p.  56. 
1868.     Allorisma  clavata  McChesney,  Trans.  Chicago  Acad.  Sci.,  vol.  1,  p. 
43,  pi.  6,  figs.  9a-b. 
This  is  the  common  species  of  Allorisma  occurring  in  the  Menard  lime- 
stone.    It  is  easily  recognized  by  its  subelliptical  outline  and  well  defined 
concentric  corrugations. 

Horizon  and  locality. — Menard  limestone,  Eandolph,  Union,  and  Pope 
counties,  Illinois. 


PLATES  AND  EXPLANATIONS 


EXPLANATION  OF  PLATE  IV 

Figs.  1-7.     Pentbemites  pbincetonensis  Ulrich p.  314 

1.  St.  Louis  limestone,  St.  Louis,  Missouri. 

2.  St.  Louis  limestone,  above  Little  Rock,  Ste.  Genevieve  County,  Missouri. 

3.  Fredonia  limestone,  Rosiclare,  Illinois. 

4-5.     Ste.  Genevieve  limestone,  Fountain  Creek,  near  Waterloo,  Illinois. 

6.  Renault  limestone,  Fairview  bluff,  below  Rosiclare,  Illinois. 

7.  Renault  limestone,  Monroe  County,  Illinois. 

Figs.  8-12.     Pentbemites  pinguis  Ulrich p.  317 

8-9.     Renault  limestone,  Monroe  County,  Illinois. 

10-11.     Shetlerville   formation,  Fairview  bluff,  Hardin   County,  Illinois. 

12.     Renault  limestone,  Fairview  bluff,  Hardin  County,  Illinois. 

Fig.  13.     Pentbemites  abctibbachiatus  Ulrich 

Renault  limestone,  mouth  of  Good  Hope  shaft,  Fairview  mine,  Rosiclare, 
Illinois. 

Figs.  14,  28-30.     Pentbemites  pulchellus  Ulrich .p.  316 

14.     Fredonia  limestone,  Cedar  Bluff,  near  Princeton,  Kentucky. 
28-30.     Shetlerville  formation,  Fairview  bluff,  Hardin  County,  Illinois. 

Fig.  15.     Pentbemites 

Shetlerville  formation,   Fairview  bluff,  Hardin  County,  Illinois. 

Figs.  16-20.     Pentbemites  buttsi  Ulrich p.  323 

16.  Renault  limestone,  mouth  of  Good  Hope  shaft,  Fairview  mine,  Rosiclare, 
Illinois. 

17.  Renault  limestone,  St.  Clair  County,  Illinois. 

18.  Renault  limestone,  Monroe  County,  Illinois. 
19-20.     Renault  limestone,  near  Anna,   Illinois. 

Figs.  21-24.     Pentbemites  pybamidatus  Ulrich p.  325 

21.     Paint  Creek  formation,  Cache  River  bluff,  Johnson  County,  Illinois. 
22-23.     Paint  Creek  formation,  two  miles  south  of  Columbia,  Illinois. 
24.     Paint  Creek  formation,  Cache  River  bluff,  Johnson  County,  Illinois. 

Fig.  25.     Pentbemites  nodosus  Hambach p.  356 

Near  base  of  Lower  Okaw  limestone,  three-fourths  of  a  mile  north  of  Mari- 
gold, Randolph  County,  Illinois. 

Figs.  26-27.     Pentbemites  symmetbicus  Hall p.  324 

Paint  Creek  formation,  one  and  one-fourth  miles  northwest  of  Floraville,  St. 
Clair  County,  Illinois. 

Figs.  31-35.     Pentbemites  godoni  DeFrance p.  319 

31-32.     The  holotype  of  the  species,  after  Parkinson. 

33-35.  Three  examples  exhibiting  some  of  the  variations,  Paint  Creek  forma- 
tion, one  and  one-fourth  miles  northwest  of  Floraville,  St.  Clair  County, 
Illinois. 

36.  Renault  limestone,  mouth  of  Good  Hope  shaft,  Fairview  mine,  Rosiclare, 
Illinois. 


Figs.  37-42.     Pentremites  platybasis  n.  sp p.  355 

37.  The  holotype  of  the  species,  with  very  flat  base.  Near  base  of  Lower 
Okaw  limestone,  three-fourths  of  a  mile  north  of  Marigold,  Randolph 
County,  Illinois. 

38.  Another  specimen  from  the  same  locality  with  a  less  nearly  flat  base. 
39-40.     Lateral  and  basal  views  of  a  third  specimen  from  the  same  locality, 

the  basal  view  showing  the  callosity  at  the  center. 
41-42.     Lower  Golconda  limestone,  Hardin  County,  Illinois. 

Figs.  43-46.     Pentremites  brevis  Ulrich p.  369 

43-44.     Lateral  and  basal  views  of  a  specimen  from  the  Upper  Okaw  limestone, 

Plum  Creek  beds,  at  Menard,  Randolph  County,  Illinois. 
45-46.     Similar  views  of  another  specimen  from  the  same  locality.     The  basal 

views  show  the  central  callosity.     Fig.  45  shows  an  abnormal  feature  in 

the  division  of  the  base  into  four  plates  instead  of  three  as  usual,  and  the 

consequent  four  lobes  of  the  callosity. 

Fig.  47.     Pentremites  godoni  DeFrance p.  319 

A  much  depressed  variety  from  the  Paint  Creek  formation,  one  and  one- 
fourth  miles  northwest  of  Floraville,  St.  Clair  County,  Illinois. 


Illinois  State  Geological  Survey 


Bulletin  No.  41,  Plate  IV 


#   ^    )    9    fy   ^  $ 


3  3 


$   3 


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8 


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16 


21 


36 


31 


37 


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10 


11 


12 


13 


14 


^ 


17 


1 


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22 


28 


32 


38 


18 


19 


20 


15 


35 


39 


40 


42 


43 


45 


46 


47 


EXPLANATION  OF  PLATE  V 

Figs.  1-4.     Platycrinus  peniciixus  Meek  and  Worthen p.  333 

1-2.     Basal  views  of  two  specimens  showing  the  three  radiating  ribs. 
3-4.     Views  of  two  radial  plates. 

Fredonia  limestone,  Cedar  Bluff  quarry,  near  Princeton,  Kentucky. 

Figs.  5-12.     DicHocEiNus  girtyi  n.  sp p    334 

5-7.     Anterior,  posterior,  and  ventral  views  of  a  very  perfect  calyx,  natural 
size. 

8.  Anterior    view    of    the    same    specimen    enlarged    to    three    and    one-half 
diameters. 

9.  Anterior  view  of  a  second  specimen.     These  two  specimens  are  cotypes. 

Shetlerville  formation,  Fairview  bluff,  Hardin  County,  Illinois. 

10.  Lateral  view  of  a  crushed  specimen. 

11-12.     Lateral  and  dorsal  views  of  the  basal  cup  of  another  specimen. 

Paint  Creek  formation,  one  and  one-fourth  miles  northwest  of  Floraville, 
St.  Clair  County,  Illinois. 

Figs.  13-14.     Dizygocrinus  superstes  Ulrich p.  329 

Lateral  and  dorsal  views  of  a  specimen  nearly  free  from  matrix. 
Fredonia  oolite,  Charles  Stone  Quarry,  near  Joppa  Junction,  Johnson  County, 
Illinois. 

Figs.  15-17.     Dizygocrinus  persculptus  Ulrich p    327 

15.     Dorsal  view  of  a  nearly  complete  cup. 

Fredonia  limestone,  Cedar  Bluff  quarry,  near  Princeton,  Kentucky. 
16-17.     Lateral  and  dorsal  views  of  a  nearly  complete  calyx. 
Fredonia  limestone,  Rosiclare,  Illinois. 

Figs.  18-23.     Globocrinus  unionensis  (Worthen) p    331 

18-19.     Lateral  and  dorsal  views  of  the  holotype.     (111.  State  Mus.  Nat    Hist 
No.  2581.) 

Near  Anna,  Union  County,  Illinois. 
20-21.     Lateral  and  dorsal  views  of  a  nearly  complete  calyx. 

Shetlerville  formation,  Fairview  bluff,  Hardin  County,  Illinois. 
22-23.     Lateral  and  dorsal  views  of  a  smaller  specimen. 

Shetlerville  formation,  four  miles  west  of  Marion,  Crittenden  County,  Ken- 
tucky. 

Figs.  24-26.     Pterotocrinus  serratus  n.  sp p    342 

24-25.     Lateral  views  of  two  "wing  plates"  showing  the  serrate  distal  border. 
Paint  Creek  formation,  Cache  River  bluff,  six  miles  south  of  Vienna,  John- 
son County,  Illinois. 
26.     Lateral  view  of  a  "wing  plate,"  the  holotype. 

Paint   Creek    formation,    two    miles    south    of   Columbia,   Monroe    County, 
Illinois. 

Figs.  27-28.     Pterotocrinus  sp. 

Lateral   views   of   two  "wing   plates."     Paint   Creek   formation,   Cache   River 
bluff,  six  miles  south  of  Vienna,  Johnson  County,  Illinois. 

Figs.  29-30.     Agassizocrinus  dissimilis  n.  sp p    344 

Posterior  and  basal  views  of  the  holotype.     Paint  Creek  formation,  one  and 
one-fourth  miles  northwest  of  Floraville,  St.  Clair  County,  Illinois. 

Figs.  31-33.     Amplexus  geniculatus  Worthen p    314 

Views   of   three   specimens.      Shetlerville   formation,    Fairview    bluff,    Hardin 
County,  Illinois. 


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EXPLANATION  OF  PLATE  VI 

Figs.  1-13.     Talarocrinus  inflatus  Ulrich p.  337 

1-3.  Posterior,  ventral,  and  dorsal  views  of  a  nearly  perfect  calyx.  Renault 
formation,  Monroe  County,  Illinois,  probably  from  the  same  locality  as 
Ulrich's  holotype. 

4-5.  Dorsal  and  lateral  views  of  a  very  perfect  dorsal  cup.  Renault  forma- 
tion, two  miles  east  of  Waterloo,  Monroe  County,  Illinois. 

6-7.  Anterior  and  ventral  views  of  a  practically  perfect  calyx.  Renault  forma- 
tion, Union  County,  Illinois. 

8.  Basal  view  of  a  dorsal  cup.  Renault  formation,  near  Bixby,  St.  Clair 
County,  Illinois. 

9-10.  Lateral  and  ventral  views  of  a  nearly  complete  calyx.  Renault  forma- 
tion, Hardin  County,  Illinois. 

11-13.  Posterior,  basal,  and  ventral  views  of  a  nearly  complete  calyx.  Re- 
nault formation,  near  Anna,  Union  County,  Illinois. 

Figs.  14-16.     Talarocrinus  planus  n.  sp p.  342 

Posterior,  right  lateral,  and  ventral  views  of  the  holotype.  Paint  Creek  forma- 
tion, three-fourths  of  a  mile  southeast  of  Commons  School,  Randolph 
County,  Illinois. 

Figs.  17-26.     Talarocrinus  trijugis  Miller  and  Gurley p.  338 

17-19.     Posterior,  anterior,  and  ventral  views  of  the  holotype.     Renault  lime- 
stone, near  Rosiclare,  Hardin  County,  Illinois. 
20-21.     Anterior    and    ventral    views    of    a    large    and    nearly    perfect    calyx. 

Renault  limestone,  Union  County,  Illinois. 
22-24.     Posterior,   dorsal   and   ventral   views   of  a  very   depressed   but   nearly 
complete  and  undistorted  calyx.     The  basal  view  suggests  T.  sexlobatus, 
but  the  tegmen  is  very  different.     Renault  limestone,  near  Anna,  Union 
County,  Illinois. 

25.  Basal  view  of  a  dorsal  cup.  Renault  limestone,  Ohio  River  bank  just 
above  the  mouth  of  Grand  Pierre  Creek,  Pope  County,  Illinois. 

26.  Basal  view  of  a  dorsal  cup.  Renault  limestone,  Cache  River  bluff,  six 
miles  south  of  Vienna,  Johnson  County,  Illinois.  The  last  two  figures  are 
indistinguishable  from  T.  inflatus  as  illustrated  in  fig.  8.  The  only  reason 
for  identifying  them  as  T.  trijugis  is  that  this  species  seems  to  be  the 
more  common  one  in  southeastern  Illinois,  while  T.  inflatus  is  more 
common  in  the  Mississippi  Valley. 

Figs.  27-33.     Talarocrinus  ovatus  Worthen p.  340 

27-30.     Posterior,  anterior,   dorsal,  and  ventral  views  of  the  holotype.     Prob- 
ably from  the  Paint  Creek  formation,  Monroe  County,  Illinois. 
31-33.     Posterior,  ventral,  and  dorsal  views  of  a  nearly  complete  calyx.     Paint 
Creek  formation,  five  miles  east  of  Waterloo,  Monroe  County,  Illinois. 

Fig.  35.     Talarocrinus  cornigerus  (Shumard) p.  340 

Lateral  view  of  a  specimen  with  stronger  ventral  spines  than  is  usual  in  the 
species.     Renault  limestone,  near  Modoc,  Randolph  County,   Illinois. 


Illinois  State  Geological  Survey 


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EXPLANATION  OF  PLATE  VII 

Figs.  1-4.     Septopora  similis  n.  sp p.  348 

1.  A  specimen  showing  the  reverse  surface,  natural  size. 

2.  A  specimen  showing  the  obverse  surface,  natural  size. 

3.  The  reverse  surface  enlarged  three  and  one-half  diameters. 

4.  The  obverse  surface  enlarged  three  and  one-half  diameters. 

St.  Louis  limestone,  above  Little  Rock,  Ste.  Genevieve  County,  Missouri. 

Figs.  5-6.     Lyropora  quincuncialis  Ulrich p.  347 

5.  A  fragment  of  the  median  portion  of  the  thickened  base,  with  a  bit  of  the 
fenestrated  portion  attached.  Shetlerville  formation,  one  mile  south  of 
Eichorn,  Hardin  County,  Illinois. 

6.  A  specimen  showing  the  thickened  base  with  a  considerable  part  of  the 

fenestrated  portion.     Upper  part  of  Renault,  "Upper  Ohara,"  Cedar  Bluff 
quarry,  near  Princeton,  Kentucky. 

Figs.  7-24.     Cystodictya  labiosa  n.  sp p.  350 

7-18.     Views    of    a    number    of    specimens    exhibiting    the    various    styles    of 

branching.     Cotypes.     Paint  Creek   formation,   one  and   one-fourth   miles 

northwest  of  Floraville,  St.  Clair  County,  Illinois. 
19.     The  specimen  shown  in  fig.  8  enlarged  three  and  one-half  diameters. 
20-22.     Three    specimens    similar   to    those   from   the    Paint   Creek    formation. 

Shetlerville    formation,    four    miles    west    of    Marion,    Crittenden    County, 

Kentucky. 
23-24.     Two  specimens  not  free  from  the  matrix.    Paint  Creek  formation,  Cache 

River  bluffs,  six  miles  south  of  Vienna,  Johnson  County,  Illinois. 

Fig.  25.     Glyptopora  punctipora  Ulrich p.  351 

Shetlerville  formation,  four  miles  west  of  Marion,  Crittenden  County,  Kentucky. 

Fig.  26.     Archimedes  cf.  swallgvanus  Hall p.  345 

Paint  Creek  formation,  Cache  River  bluffs,  six  miles  south  of  Vienna,  John- 
son County,   Illinois. 

Fif.  27.     Archimedes  compactus  Ulrich p.  346 

Paint  Creek  formation,  Cache  River  bluff,  six  miles  south  of  Vienna,  Johnson 
County,  Illinois. 

Fig.  28.     Archimedes  proutanus  Ulrich p.  346 

Paint  Creek  formation,  Cache  River  bluffs,  six  miles  south  of  Vienna,  Johnson 
County,   Illinois. 

Fig.  29.     Archimedes  distans  Ulrich p.  346 

Paint  Creek  formation,  Cache  River  bluffs,  six  miles  south  of  Vienna,  Johnson 
County,  Illinois. 

Fig.  30.     Archimedes  meekanus  Hall p.  346 

Paint  Creek  formation,  Cache  River  bluffs,  six  miles  south  of  Vienna,  Johnson 
County,  Illinois. 

Figs.  31-o2.     Archimedes  communis   Ulrich p.  347 

Paint  Creek  formation,  Cache  River  bluffs,  six  miles  south  of  Vienna,  Johnson 
County,  Illinois. 


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EXPLANATION  OF  PLATE  VIII 

Figs.  1-4.     Pugxoides  ottumwa   (White) p.  351 

1-2.     Brachial  and  pedicle  views  of  one  specimen.     Ste.  Genevieve  limestone, 

near  mouth  of  River  aux  Vases,  Ste.  Genevieve  County,  Missouri. 
3-4.     Similar  views  of  another  specimen,  Fredonia  limestone,  Rosiclare,  Hardin 

County,  Illinois. 

Figs.  5-6.     Rhipidomella  dubia  (Hall) p.  351 

Brachial  and  pedicle  views  of  two  specimens.  Fredonia  limestone,  Rosiclare, 
Illinois. 

This  species  is  a  common  one  in  the  Mississippian  formations  from 
the  Keokuk  to  the  Ste.  Genevieve,  but  neither  the  species  nor  the  genus 
has  been  observed  in  any  of  the  Chester  formations  of  Illinois. 

Figs.  7-14.     Spiriferixa  subspixosa  n.  sp p.  352 

Pedicle  and  brachial  views  of  four  different  specimens  exhibiting   range  in 

size. 
7-10.     Shetlerville  formation,  four  miles  west  of  Marion,   Crittenden   County, 

Kentucky. 
11-14.     Shetlerville  formation,  Fairview  bluff,  Hardin  County,  Illinois. 

Figs.  15-16.     Spiriferixa  spixosa  (Norwood  and  Pratten) p.  353 

15.  Brachial  view,  Paint  Creek  formation,  one  and  one-fourth  miles  north- 
west of  Floraville,  St.  Clair  County,  Illinois. 

16.  Pedicle  view,  Paint  Creek  formation,  Cache  River  bluffs,  six  miles  south 
of  Vienna,  Johnson  County,  Illinois. 

Figs.  17-18.     Spiriferixa  transversa   (McChesney ) p.  353 

Brachial  and  pedicle  views  of  two  individuals.  Shetlerville  formation,  Lemon 
quarry,  three  miles  west  of  Marion,  Crittenden  County,  Kentucky. 

Figs.  19-20.     Composita  trixuclea   (Hall) p.  354 

Brachial  and  pedicle  views  of  an  average  specimen.  Shetlerville  formation, 
Fairview  bluff,  Hardin  County,  Illinois. 

Figs.  21-24.     Cliothyridixa  sublamellosa    (Hall) p.  354 

Two  pedicle  and  two  brachial  views  of  four  different  individuals.  Shetlerville 
formation,  Fairview  bluff,  Hardin  County,  Illinois. 

Figs.  25-28.     Mesoblastus  glaber  (Meek  and  Worthen) p.  327 

Lateral  views  of  four  different  individuals,  magnified  three  and  one-half 
diameters.     Shetlerville  formation,  Fairview  bluff,  Hardin  County,  Illinois. 

Figs.  29-34.     Mesoblastus  incurvatus  n.  sp p.  358 

29-31.     Lateral  views  of  three  specimens. 

32-34.  Lateral  views  of  the  same  specimens  magnified  three  and  one-half 
diameters.  Golconda  limestone,  NE.  %  sec.  28,  T.  12  S.,  R.  7  E.,  near  Flat 
Rock  ford,  Pope  County,  Illinois. 

AFig.  35.     Pachylocrixus  cachexsis  n.  sp p.  343 

Paint  Creek  formation,  Cache  River  bluffs,  six  miles  south  of  Vienna,  Johnson 
County,  Illinois. 

This  species  is  also  present  in  the  Paint  Creek  formation  of  Monroe 
County,  Illinois. 


Figs.  36-39.     Pterotocrinus  capitalis  Lyon p    360 

36.     Lateral  view  of  a  cast  of  the  holotype.     Golconda  limestone,  Crittenden 

County,  Kentucky. 
37-38.     Lateral  views  of  two  "wing  plates."     Lower  Golconda  limestone,  three 

and  one-half  miles  southeast  of  Vienna,  Johnson  County,  Illinois. 
39.     Lateral  view  of  a  "wing  plate."     Lower  Golconda  limestone,  Ohio  River 

bluffs,  above  Golconda,  Pope  County,  Illinois. 


Illinois  State  Geological  Survey 


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EXPLANATION  OF  PLATE  IX 

Figs.  1-6.     Bellerophon  chesterexsis  n.  sp p.  365 

1-3.     Three  views  of  a  nearly  perfect  specimen.     The  holotype.     Basal  Okaw 

limestone,  Camp  Creek,  Randolph  County,  Illinois. 
4-6.     Three   similar   views    of   another   specimen.      Basal   Golconda   limestone, 

three  and  one-half  miles  southeast  of  Vienna,  Johnson  County,  Illinois. 

Figs.  7-10.     Euphemus  randolfhensis  n.  sp p.  365 

7.  View    of    the    holotype.      Basal    Okaw    limestone,    Camp    Creek,    Randolph 

County,  Illinois. 

8.  Similar  view  of  another  specimen.     Basal  Golconda  limestone,  three  and 
one-half  miles  southeast  of  Vienna,  Johnson  County,  Illinois. 

9-10.     Two  views  of  a  third  specimen,  from  the  same  locality  as  the  last. 

Figs.  11-14.     Nucula  PLATYNOTUS  n.  sp p.  361 

11-12.     Lateral  and  dorsal  views  of  a  practically  perfect  shell.     The  holotype. 
Basal  Golconda  limestone,  three  and  one-half  miles  southeast  of  Vienna, 
Johnson  County,  Illinois. 
13-14.     Lateral  and  dorsal  views  of  a  nearly  complete  shell.     Basal  Okaw  lime- 
stone, Camp  Creek,  Randolph  County.  Illinois. 

Figs.  15-20.     Bucanopsis  ornatus  n.  sp p.  366 

15-16.     Two  views  of  an  incomplete  specimen.     Basal  Okaw  limestone,  Camp 
Creek,  Randolph  County,  Illinois. 

17.  Dorsal  view  of  the  holotype.     Basal  Golconda  limestone,  three  and  one- 
half  miles  southeast  of  Vienna,  Johnson  County,  Illinois. 

18.  Dorsal  view  of  a  somewhat  larger  specimen  from  the  same  locality. 
19-20.     Lateral  and  dorsal  views  of  another  specimen,  from  the  same  locality 

as  the  last  two. 

Figs.  21-23.     Conocardium  chesterensis  n.  sp p.  364 

21.     Lateral  view  of  the  holotype.     Basal  Golconda  limestone,  three  and  one- 
half  miles  southeast  of  Vienna,  Johnson  County,  Illinois. 
22-23.     Lateral    views    of    two    valves,    basal    Okaw    limestone,    Camp    Creek, 
Randolph  County,  Illinois. 

Figs.  24-30.     Nucula  randolphensis  n.  sp p.  362 

24-25.     Lateral  and  dorsal  views  of  the  holotype.    Basal  Okaw  limestone,  Camp 

Creek,  Randolph  County,  Illinois. 
26-27.     Lateral  and  dorsal  views  of  another  nearly  perfect  specimen.     Basal 
Golconda  limestone,  three  and  one-half  miles  southeast  of  Vienna,  John- 
son County,  Illinois. 
28-30.     Lateral  views  of  three  specimens,  from  the  same  locality  as  the  last. 

Figs.  31-34.     Leda  chesterensis  n.  sp p.  363 

31-32.     Lateral   views   of   two    valves.      Basal    Golconda   limestone,    three   and 

one-half  miles  southeast  of  Vienna,  Johnson  County,  Illinois. 
33-34.     Lateral   views    of    two   valves.      Basal    Okaw    limestone,    Camp    Creek, 

Randolph  County,  Illinois. 

Figs.  35-36.     Camarophoria  explanata    (McChesney) p.  360 

Pedicle   and   brachial   views   of  two   specimens.     Golconda   limestone,   Hardin 
County,  Illinois. 


Pigs.  37-38.     Composita  trinuclea  (Hall) p.  361 

Brachial  and   pedicle  views  of  two   specimens.     Golconda  limestone,   Hardin 
County,  Illinois. 

Pigs.  39-41.     Gliothyridina  sublamellosa    (Hall) p.  360 

39-40.     Brachial     and   pedicle  views  of  two  specimens.     Golconda  limestone. 

Hardin  County,  Illinois. 
41.     View  of  a  pedicle  valve  upon  which  the  concentric,  lamellose  expansions 

of  the  shell  are  well  shown.     Golconda  limestone,  Hardin  County,  Illinois. 


Illinois  State  Geological  Survey 


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EXPLANATION  OF  PLATE  X 

Figs.  1-3.     Pentremites  obesus  Lyon p.  355 

1-2.     Lateral  and  ventral  views  of  a  nearly  complete  specimen.     Lower  Gol 

conda   limestone,   quarry    of   Golconda   Portland    Cement   Company,    Pope 

County,  Illinois. 
3.     Lateral  view  of  a  large  specimen,  incomplete  at  the  base.    Lower  Golconda 

limestone,  Ohio  River  bank  above  Golconda,  Pope  County,  Illinois. 

Fig.  4.     Pentremites  fohsi  Ulrich p.  370 

Lateral  view  of  a  nearly  complete  specimen.  Lower  part  of  Menard  limestone, 
three   and   one-half   miles   northwest   of   Golconda,   Pope   County,   Illinois. 

Figs.  5-7.     Pentremites  okawensis  n.  sp p.  357 

5.  Lateral  view  of  a  nearly  complete  specimen.     Lower  Okaw  limestone,  three- 

fourths  of  a  mile  north  of  Marigold,  Randolph  County,  Illinois. 

6.  Lateral  view  of  another  nearly  complete  specimen.     Golconda   limestone, 

Hardin  County,  Illinois. 

7.  Lateral  view  of  a  somewhat  weathered  specimen.     Glen  Dean  limestone, 

Hardin  County,  Illinois. 

Fig.  8.     Pentremites  spicatus  Ulrich p.  368 

Lateral  view  of  a  nearly  complete  specimen.  Upper  Okaw,  Plum  Creek  beds, 
Menard,  Randolph  County,  Illinois. 

Figs.  9-10.     Pentremites  gemmiformis  Hambach p.  326 

Lateral  views  of  two  nearly  perfect  specimens.  Paint  Creek  formation,  three 
miles  east  of  Prairie  du  Rocher,  Randolph  County,  Illinois. 

Figs.  11-13.     Pentremites  cherokeeus  Hall p.  371 

Lateral  views  of  three  specimens.  Fig.  13  shows  the  very  prominent  extended 
points  of  the  deltoid  plates,  which  are  commonly  destroyed.  Upper  part 
of  Menard  limestone,  Mississippi  River  bluff,  five  miles  below  Chester, 
Randolph  County,  Illinois. 

Fig.  14.     Pterotocrinus  bifurcatus  Wetherby p.  372 

Ventral  view  of  the  holotype,  showing  the  five  "wing  plates"  in  place.  Glen 
Dean  limestone,  Sloans  Valley,  Pulaski  County,  Kentucky. 


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EXPLANATION  OF  PLATE  XI 

Figs.  1-2.     Sulcatopinna  missouriensis   (Swallow) p.  375 

Lateral  views  of  two  specimens,  neither  of  which  is  complete.  Menard  lime- 
stone, tributary  of  Gravel  Creek,  four  miles  northeast  of  Chester,  Ran- 
dolph County,  Illinois. 

Figs.  3-4.     Allorisma  clavata  McChesney p.  377 

Lateral  views  of  two  specimens.  Menard  limestone,  tributary  of  Gravel  Creek, 
four  miles  northwest  of  Chester,  Randolph  County,  Illinois. 

Figs.  5-8.     Prismopora  serrulata  Ulrich p.  373 

5.     View  of  a  well  preserved  specimen,  showing  the  branching  of  the  colony. 
Upper  Okaw  limestone,  Plum  Creek  beds,  one  mile  east  of  Preston,  Ran- 
dolph County,  Illinois. 
6-8.     Views  of  three  fragments  of  branches.     Glen  Dean  limestone  three  miles 
east  of  Cloverport,   Breckenridge   County,  Kentucky. 

Fig.  9.     Pterotocrinus  menardensis  n.  sp p.  373 

View  of  a  very  perfect  "wing  plate,"  the  holotype.  Menard  limestone,  east 
of  Cobden,  Union  County,  Illinois. 

Fig.  10.     Spirifer  increbescens  Hall p.  374 

Pedicle  view  of  a  large  specimen.  Clore  limestone,  four  miles  northwest  of 
Golconda,  Pope  County,  Illinois. 

Fig.  11.     Batostomelea  nitidula  Ulrich p.  373 

View  of  a  portion  of  a  slab  containing  many  examples  of  this  species.  Lower 
Clore  limestone,  Union  County,  Illinois. 

Figs.  12-14.     Composita  subquadrata    (Hall) p.  375 

12-13.     Pedicle  and  brachial  views  of  a  nearly  perfect  specimen.     Clore  lime- 
stone, four  miles  northwest  of  Golconda,  Pope  County,  Illinois. 
14.     Pedicle  view  of  a  larger  specimen,  from  the  same  locality. 


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INDEX 

Italics  refer  to  synonyms.  Roman  numerals  refer  to  plates  on  which  illustrations  are 
given.  Bold  face  numerals  in  parenthesis  indicate  special  mention,  in  most  cases  careful 
description  of  the  forms,  and  their  geographic  and  geologic  occurrence. 

PAGE 

Acanthotelson  eveni 89 

Acervularia  davidsoni  E.  and  H 85 

"Acid  spar ",  definition  of 285 

Aclisina  pvgmaea  (Weller) 119 

Agassizocrinus 172,  183,  184,  186,  207,  215 

A.  dissimilis  n.  sp (344),  V 

Agriculture,  importance  of 19 

relation  of,  to  topography 43-44 

Alethopteris  decurrens  (Artis) 227 

A.  grandifolia  Newberry 227 

A.  lonchitica  (Sch.)  (Ohio  form) 227 

Allorisma 123,  124,  138,  222 

A.  clavatum  McChesney 208,  (377),  XI 

Alluvial  deposits 232-233 

Amplexus  geniculatus  Worthen 137,  139,  140,  141,  142,  145,  156,  (3  1 4),  V 

Amphigenia  curta  (Meek  and  Worthen) 86 

Anisotrypa  solida  Ulrich 183 

A.  ?sp 137 

Annex  mine,  description  of 297-298 

Annex-Extension  vein,  description  of 250 

Archaeocidaris 117,  118,  207,  208,  215 

Archimedes 138,  150, 158,  164,  171,  172, 174,  178,  185,  186,  214,  215,  (344) 

A.  cf.  swallovanus  Hall 170,  (345),  VII 

A.  communis  Ulrich 171,  173,  182,  196,  (347),  VII 

A.  compactus  Ulrich 171,  172,  173,  183,  185,  (346),  VII 

A.  confertus  Ulrich 182 

A.  distans  Ulrich 171,  173,  195,  196,  207,  (346),  VII 

A.  lativolvis  Ulrich 182,  186 

A.  laxus 197,  198 

A.  meekanus  Hall 170,  173,  207,  (346),  VII 

A.  proutanus  Ulrich 170,  173,  183,  (346),  VII 

A.  proutanus  Ulrich,  var 207 

A.  swallovanus  Hall 182,  183, 185,  186,  195,  207,  (345) 

A.  terebriformis  Ulrich 182,  183,  196,  207 

"Archimedes  limestone ",  definition  of 122-123 

Ascodictyon  sp 137 

Asterocrinus  capitalis  Lyon 360 

Athyris  densa  Hall 99,  100 

A .  sublamellosa  Hall 354 

A .  subquadrata  Hall 375 

Atrypa  spinosa  Hall  ? : 86 

Aviculopectin  sp 95,  171,  185,  222 

Bain,  H.  Foster,  work  of 276-277 

Bald  Hill  anticline,  relation  of  to  oil  and  gas  possibilities 308-309 

Baldwin  mine 302 

Barite,  occurrence  of 254 

Basal  conglomerate,  definition  of 27 

Batostomella 148,  171,  173,  196,  215 

B.  nitidula  Ulrich 214,  215,  (373),  XI 

B.  ?  sp 137, 183,  207 

403 


404  INDEX 

PAGE 

Battery  Rock  coal 226-227 

Battery  Rock  Township,  limestone  sinks  in 41 

topographic  age  of  hills  in 48-49  50 

Bedded  fluorspar  deposits,  description  of 254-256 

methods  used  in  mining  of 283 

Bell  coal 228 

Bellerophon 89,  116,  117,  119,  138,  215,  222 

B.  chesterensis  n.  sp 185,  (365),  IX 

B.  monroensis  Weller  ? 119 

Bethel  sandstone,  description  of 159-164 

Big  Creek,  description  of 21 

Glen  Dean  fossils  collected  along 195 

outcrop  of  Warsaw  formation  on ■ 98 

relation  of  to  faults 64 

Big  Creek  fault,  description  of 71-72 

Big  Joe  mine 302 

Birds  Point,  detailed  section  at 163 

1  Blanket"  formations,  see  Bedded  fluorspar  deposits. 
"Blende",  see  Sphalerite. 

Blue  Diggings  fault,  description  of 71 

Blue  Diggings  mine,  description  of 298 

Blue  Diggings  vein,  description  of 250 

inclination  of 64 

Brachythyris  subcardiiformis  (Hall)? 99,  100 

B.  suborbicularis  (Hall)? 99 

Bryozoans  (several  undet.  spec.) 185,  207 

Bucanopsis  ornatus  n.  sp 185,  (366),  IX 

B.  textilis  (Hall) 119,  120 

Bulimorpha  sp 117,  119 

B.  whitfieldi  Weller 117,  119 

Buzzards  Point  plain 47-48 

Cache  River  bluffs,  Renault-Bethel  contact  shown  in 146 

"Calc",  see  Calcite. 

Calcite,  deposition  of 257-258 

description  and  occurrence  of 253 

Camarophoria  explanata  (McChesney) .  183,  184, 185, 186, 195,  196,  207,  214,215,  222,  (360),  IX 
Camarotoechia  mutata  (Hall)? 99 

C.  tethys  (Billings)  ? 86 

Caninia  n.  sp 170,  173 

Cardiopteris  polymorpha  Gopp 201 

Cardiocarpon  sp.  ? 227 

Carmens  store,  fault  near 71 

Carrsville,  Daisy  fault  near 71 

Caseyville  formation,  description  of 225-228 

Cave  in  Rock,  limestone  sinks  near 41 

Renault-Bethel  contact  near 145 

St.  Louis  limestone  near 102,  105 

Cave  in  Rock  mine,  description  of 301 

Cave  in  Rock  Township,  topographic  age  of  hills  in 48-49,  50,  51 

Cement,  materials  for 305 

Cenozoic,  definition  of 27 

'  'Center  slips  ",  relation  of  to  mineralization 258 

Ceramics  industry,  importance  of  fluorspar  in 288 

Cerussite,  occurrence  of 255 

relation  of  to  mineralization 259 

Chalcopyrite,  deposition  of 258 

description  of 254 

Chattanooga  shale,  correlation  of 89 

description  of 87-90 

Cheilanthites  cf .  macilenta 227 

Chemical  industries,  importance  of  fluorspar  in 288 

Chester  group,  description  of 121-131 


INDEX  405 

PAGE 

Chonetes  cf.  chesterensis  Weller 171,  172, 174 

C.  coronatus  (Conrad) 86 

C.  mesolobus 229 

Cladodus  sp 185 

Clement  mine,  description  of 298 

Cliffs,  distribution  of .  46-47 

Cliothyridina  hirsuta  (Hall)  ? 99 

C.  sublamellosa  (Hall) 138,  139,  141,  148,  158, 

171,  173,  182,  183,  184,  185,  195,  196,  208,  222,  (354,360-361),  VIII.  IX 

C.  sublamellosa  (Hall)  ? .215 

C.  aff.  sublamellosa  (Hall) 116,  117,  118 

Clore  limestone,  description  of 212-216 

Coeloconus  sp 185 

Composita  subquadrata  (Hall) 208,  209,  214,  215,  (375),  XI 

C.  trinuclea  (Hall) 116,  117,  118,  119,  138,  139,  141,  148, 

158, 171, 173,  182,  183,  184,  185, 195,  196,  208,  222,  (354,  361,  375),  VIII,  IX 

Conocardium  chesterensis  n.  sp 185,  (364-365),  IX 

Conularia  sp 138,  196,  208 

Cornulites  sp 137,  183 

Correlation  methods 150-151,  155 

Crania  chesterensis  Miller  and  Gurley 138,  141,  183,  207,  215 

Crinoids,  plates  and    terns 137,  185,  207 

Cross-bedding,  significance  of 24 

Curlew  coal 228-229 

Cyathophyllum  rugosum  Hall 85 

Cycle  of  erosion,  definition  of 35 

Cycloceras  cf.  sequoyahensis  Snider 185 

C.  sp 185 

Cypress  sandstone,  description  of 175-178 

Cypricardinia  indianensis  Hall 119 

Cypricardella  oblonga  Hall 119 

C.  sp 117,  118 

Cyrtina  ??  sp 138 

Cystelasma  quinqueseptata 116 

Cystodictya  labiosa  n.  sp.  (Ulrich) .  .  138,  139,  140,  148,  157,  170,  171,  172,  173,  174,  (350),  VII 

Cystiphyllum  lineata  Ulrich 99 

C.  pustulosa  Ulrich 99 

C.  sp 85 

Daisy  fault,  relation  of  to  fluorspar  deposits 71 

Daisy  mine,  description  of 295 

Decadocrinus  columbiensis  (Worthen) 170,  173 

Degonia  sandstone,  description  of 216,  218 

Devonian  chert,  description  of 85 

Devonian  limestone,  association  of  fluorspar  with 87 

description  of 84-87 

possibility  of  oil  in 309 

Diaphragmus 164 

D.  elegans  (Norwood  and  Pratten) 

138,  139,  141,  148,  158,  170,  173,  182,  183,  185,  195,  196,  207,  215,  222 

D.  n.  sp 117,  118 

D.  ?sp 214 

Dichocrinus  girtyi  n.  sp 137,  (334),  V 

Dichotrypa  sp 99 

Dielasma  formosa  (Hall) 116,  118 

D.  illinoisensis  Weller 138,  139.  141,  171,  173 

D.  shumardanum  (Miller) '.  196,  207,  214 

D.  sp 117,  1 18,  182,  183,  185 

Dikes,  definition  of 29 

Dip,  definition  of 31 

Discitoceras  sp 185 

Dizygocrinus  persculptus  Ulrich 117,  (327),  V 

D.  sp.  undet 116 

D.  superstes  Ulrich (329),  V 

Dolatocrinus  sp 85 


406  I NDEX 

PAGE 

Downeys  Bluff  sill  and  dike,  description  of 239-241 

Drainage,  types  of 21 

Eatonia  sp 86 

Economic  geology 247-310 

Elizabethtown,  Fredonia  limestone  outcrop  near 110-111,  112 

limestone  sinks  near 41 

population  of 20 

topographic  age  of  hills  near 51 

Elizabethtown  plain 50-51 

Emmons,  S.  F.,  work  of 275 

Empire  mine,  description  of 301-302 

Encrina  godoni  Def ranee 31 9 

Encrinites  florealis  von  Schlotheim 31 9 

English  fluorspar  deposits,  competition  with 290 

Eotrochus  n.  sp 117,  1 19 

Epoch,  definition  of 27 

Era,  definition  of 27 

Eridopora  punctifera  Ulrich 137,  139,  140,  182,  183,  196,  207 

Eumetria  costata  (Hall) 138,  141,  207,  208,  214,  215,  222 

E.  vera  (Hall) 138,  139,  141,  171,  173,  183,  185,  195,  196 

E.  verneuiliana  (Hall) 99,  117,  118 

Euomphalus  planidorsatus  Meek  and  Worthen 183 

E.  sp .215 

Eupachycrinus  maniformis  (Yandell  and  Shumard) 170,  173 

E.  sp 137,  195 

Euphemus  randolphensis  n.  sp 185,  (365-366),  IX 

Eureka  prospect,  association  of  with  Peters  Creek  faults 70 

Extension  mine,  description  of 297-298 

Extension  vein,  inclination  of 64 

Fairview,  igneous  rock  near 239 

Fairview  bluff,  Renault  fossils  from 148 

Fairview  Mill,  description  of 285 

Fairview  mine,  occurrence  of  stibnite  in 254 

description  of 295-298 

Farming,  relation  of  to  topography 43-44 

Faulted  zones,  description  of 55,  58,  60-64 

Faulting,  association  of  fluorspar  deposits  with 55,  275 

Faulting,  criteria  for  recognition  o 58-59 

Faulting,  definition  of 30 

kinds  of 30-31 

magnitude  of 56-57 

Fault  planes,  inclination  of 64 

Fenestella  (Archimedes)  meekana  Hall 3!fi 

F.  (Archimedes)  swallovana  Hall 31+5 

F.  cestriensis  Ulrich 137,  139,  140,  148,  157,  171,  173,  183 

F.  elevatipora  Ulrich 137,  140,  183 

F.  elevatipora  Ulrich  ? 215 

F.  (Lyropora)  quincuncialis  Hall SJfl 

F.  serratula  Ulrich 117,  118,  138,  139,  140,  148,  157,  171,  173,  183,  196,  207 

F.  serratula  Ulrich  ? 214,  215 

F.  sp 171,  182,  183,  185,  195,  196,  207,  215 

F.  tenax  Ulrich 99,  117,  118,  138,  139,  140,  148,  157,  171,  173,  183 

F.  tenax  Ulrich  ? 214 

Fertilizer,  materials  for 305 

Fish  teeth  (several  species) 185 

Fistulipora  excelens  Ulrich 137,  140,  171,  173,  183,  207 

F.  sp 117,  118,  195,  196 

Fluorspar  and  fluorspar  deposits,  commercial  grades  of 289 

deposition  of 258 

description  of 252 

discovery  of 247 


INDEX  407 

PAGE 

Fluorspar  and  fluorspar  deposits,  economic  geology  of 247-304 

geologic  history  of 281-282 

igneous  rocks  and  faulting  in  association  with 55,  66 

milling  of 283-289 

mining  of 282-283 

occurrence  of 248-257 

origin  of 275-281 

production  of 289-290 

uses  of 287-289 

Fohs,  F.  J.,  work  of 277 

Formations,  definition  of 25 

significance  of 25-26,  27 

Fossils,  significance  of 26 

Fossil  lists,  Clore  limestone 214,  215 

Devonian  limestone 85-86 

Fredonia  limestone  member 116-118 

Glen  Dean  limestone 195,  196 

Golconda  formation 182,  183,  185 

Kinkaid  limestone 222 

Menard  limestone 207,  208 

Paint  Creek  formation 170-171 

Renault  formation 148,  149 

Ste.  Genevieve  limestone 116,  117,  118 

Shetlerville   ormation 137-141 

Tar  Springs  sandstone 201 

Fredonia  limestone  member,  lithologic  character  of 110,  111 

relation  of  sink  holes  to    41 

thickness  of 113-114 

Fruit  raising,  desirability  of 45-46 

Galena,  deposition  of 258 

description  of 253 

separation  of 283 

Gastropods 171 

Geography 39-52 

Genus  Globocrinus (330) 

Genus  Talarocrinus (336) 

Geologic  map,  description  and  explanation  of 36-37 

use  of  in  prospecting 291 

Geologic  time,  definition  of 27 

'  divisions  of 28 

Girtyella  brevilobata  (Swallow) 138,  141,  182,  183,  196 

G.  indianensis  (Girty) 117,  118,  138,  139,  141,  171,  173,  215 

G.  sp 222 

Glacial  drift,  absence  of 44 

Glen  Dean  limestone,  description  of 191-198 

Globocrinus  n.  genus (330) 

G.  unionensis  (Worthen) 137,  140,  142,  (33  1 ),  V 

Glyptopora  cf .  punctipora  Ulrich 171 

G.  punctipora  Ulrich.  . 138,  139,  141,  170,  172,  173,  174,  (35  1 ),  VII 

Golconda  and  Lower  Okaw  species,  description  of 355-367 

Golconda  dike,  description  of 241 

Golconda,  Clore  fossils  near 215 

Paint  Creek  formation  near 168,  171 

Glen  Dean  fossils  collected  near 196 

igneous  rock  near 241 

Menard  fossils  near 207-208 

sections  near 168,  205-206 

Golconda  formation,  description  of 178-187 

Goodhope  mine,  description  of 295-297 

Goodhope  shaft,  Renault  fossils  from 148,  149 

Goodhope  vein,  description  of 250 

inclination  of - 64 


408  INDEX 

PAGE 

Goose  Creek,  fluorspar  in  Devonian  strata  near 87 

outcrop  of  Chattanooga  shale  on 88 

of  Osage  formation  on 94 

Granatocrinus  glaber  Meek  and  Worthen 327 

"Gravel"  deposits  of  fluorspar,  see  Superficial  fluorspar  deposits. 

"Gravel  spar",  definition  of 283 

Griffithides  sp 95 

Groups,  definition  of 27 

Hamp  mines,  description  of 302,  303 

Hardinsburg  sandstone,  description  of 187-190 

Harris  Creek,  relation  of  to  limestone  sinks 41 

Harts  Store,  coal  near 228 

Hederella  sp 137 

Heliphyllum  sp 85 

Hemitrypa  proutana  Ulrich 99 

Herrin  fault,  description  of 66 

Hexacrinus  leai  (Lyon) 85,  86 

Hicks,  fluorspar  in  Devonian  strata  near 87 

outcrop  of  Devonian  strata  near 84 

topographic  age  of  hills  near 48-49 

Hicks  Branch,  outcrop  of  Warsaw  formation  on 98 

Hicks  Dome,  Chattanooga  shale  on 88 

description  of 65 

distribution  of  formations  around 81 

origin  of 29-30 

outcrop  of  Osage  formation  on 93 

of  Warsaw  formation  on 97 

relation  of  to  oil  and  gas  possibilities 307-308 

High  Knob,  altitude  of .  .  : 20 

topographic  age  of 47 

Hicks  mine 302 

Hillside  mine,  description  of 298 

History  of  mining  development 247-248 

Hogthief  Creek,  relation  of  to  faults 64 

Hogthief  Creek  fault,  description  of 68 

Holopea  sp 185 

H.  ?  sp 138 

Horton  Hill  anticline,  relation  of  to  oil  and  gas  possibilities 308-309 

Hosick  Creek,  relation  of  to  limestone  sinks 41 

Hutchinson  mine 302 

Hydreionocrinus  sp 170,  173,  207,  208 

Hydrocarbon,  occurrence  of  with  fluorspar 254 

Igneous  rocks 23,  29,  237-244 

association  of  fluorspar  deposits  with 55,  275 

Illinois  Furnace,  faulting  nea  71-73 

iron  deposits  near 304 

St.  Louis  limestone  near 105 

Indian  Point,  detailed  section  at 162 

Paint  Creek  fossils  from 170-171 

Iron  ore  deposits 304-305 

"Jack",  see  Sphalerite. 

Jacks  Point  quarry,  description  of 306 

Jenkins  Point,  pre-Denonian  pebbles  found  near 79 

Joplin  jigs,  use  of 283 

Karbers  Ridge,  section  of  Kinkaid  limestone  near 221 

Karbers  Ridge  plain 48-49 

Karst  topography,  definition  of 41 

Kentucky,  faulting  in 55 

Kinkaid  limestone,  description  of 218-222 


INDEX  409 

PAGE 

Kindle,  E.  M.,  work  of  on  Devonian 83 

Knorria 125 

Laevidentalium  venustum  (Meek  and  Worthen) 117, 119 

Lamprophyre,  description  of 237 

Lead  Hill,  bedded  fluorspar  deposit  at 254 

Lead  Hill  mines,  description  of 300-301 

Lead  Hill  prospect,  association  of  with  Peters  Creek  faults 70 

Leda  chesterensis  n.  sp (363-364),  IX 

L.       curta  Meek  and  Worthen 119 

L.      sp 117, 185 

Lee  fault,  description  of 66-67 

Lee  mine,  description  of 303 

Lepetopsis  levettei  White 117,  118 

L.  sp 185 

Lepidodendron 125, 177,  201 

L.  cf .  modulatum 212 

Leptaena 89 

L.  rhomboidalis  (Wilck) 86 

Lime,  materials  for 305 

Limestone,  economic  geology  of 305-306 

Limestone,  origin  of '. 25 

solution  of , 33 

Limestone  sinks 40-42 

Lioclema  sp 171,  173,  215 

L.  ?  araneum  Ulrich 183,  215 

Lithostrotion 97, 105 

L.  canadensis 105 

L.  harmodites 116 

L.  proliferum 105 

Loess,  definition  of 45 

Loess  deposits 233-234 

Lower  Chester  formations,  correlation  of 132 

Lower  Chester  and  related  species,  description  of 314 

Lower  Mississippian  strata,  description  of 91-120 

"Lower  Ohara"  limestone  member,  lithologic  character  of 112 

thickness  of 114 

Lower  Okaw  species,  description  of 355,  367 

Lyropora 149,  150,  158,  172,  194 

L.  quincuncialis  Hall (347) 

L.  ranosculum 149,  157,  170,  173 

L.  sp 99,  148,  207 

L.  subquadrata 149,  157 

McFarland  plain 49-50 

McFarland  Township,  limestone  sinks  in 41 

topographic  age  of  hills  in 48-49,  50,  51 

Malachite,  occurrence  of 254 

Marginif era  muricata 229 

Martha  Furnace,  iron  deposits  near 304 

Martin  mine,  description  of 300 

Martin  prospect,  association  of  with  Peters  Creek  faults 70 

Martinia  contracta  Meek  and  Worthen 183,  185,  196,  197,  222 

M.  sp 182 

M.  sulcata  Weller 183 

Meekopora  eximia  Ulrich 148,  157,  196 

M .  sp 207 

Megalopteris  sp.  ? 227 

Melcher  Hills,  topographic  age  of 47,  49 

Members,  definition  of 27 

Menard  limestone,  description  of 202-209 

Meramec  group,  definition  of 96-97 

Meristella  haskinsi  Hall  ? 86 


410 


INDEX 


PAGE 

Mesoblastus  glaber  (Meek  and  Worthen) 137,  140,  148   157  (327)  VIII 

M .  glaber  f  Ulrich '....' '.  .  327 

M.  incurvatus  n.  sp (358-359),  VIII 

Mesozoic,  definition  of '      27 

Metallurgical  industries,  importance  of  fluorspar  in 288 

Metasomatic  relations  of  minerals 259 

Mica-peridotite,  description  of 237 

Michelinia 85 

M.  princetonensis 115  116 

M.  stylopora  Eaton  ? 86 

M.  subramosa 116 

Middle  Chester  formations,  correlation  of 132 

Miller  mine,  description  of 300 

Milling  methods 283-289 

Mineralization  along  fault  planes 60 

Minerals,  metasomatic  relations  of 259 

paragenesis  of 257-274 

replacements  of 259-260 

of  the  bedding  deposits • 255 

of  the  vein  deposits 252-254 

Mines,  descriptions  of 293-304 

Mining  methods 282-283 

Mississippian  chert,  description  of 85 

Mississippian  System,  definition  and  nomenclature  of 91 

Mix  dike,  description  of 241 

Monroe  County,  early  subdivisions  of  the  Chester  in 127 

Monroe  Township,  topographic  age  of  hills  in 50 

Mourlonia  sp 185 

Myalina  sp 116,  117,  118,  138,  185,  208 

Naticopsis  sp 116,  117,  118,  119,  222 

Nautilus  sp 185 

N.  ?  sp 183 

Neuropteris  cf .  obliqua 227 

New  Madrid  earthquake,  relation  of  to  Hardin  County  faulting 55 

Nuclcocrinus  verneuili 85,  86 

Nucula  illinoiensis  Worthen 119 

N.  platynotusn.  sp 185,  (361),  IX 

N.         randolphensis  n.  sp 185,  (362-363),  IX 

N.         shumardana  Hall 117,  118 

N.         sp 185 

Ohio  River  flood  plain 19,  51-52 

Oil  and  gas  possibilities 307-310 

Onondaga  limestone,  possibility  of  oil  in 309 

Optical  fluorite 288 

Orbiculoidea  sp ' '. 182,  196 

Orrs  Landing  dike,  description  of 237-239 

Orthis  dubia  Hall 351 

Orthoceras  cf .  okawense  Meek  and  Worthen 185 

O.  sp 116,  117,  118,  119,138,222 

Orthonychia 138,  148,  171 

O.  acutirostra  (Hall) 119,  120 

O.  chesterensis  Meek  and  Worthen 183 

O.  cf.  chesterensis 173 

Orthotetes kaskaskicnsis  (McChesney)..  .117,  118,  138,  148,  170,  182,  183,  185,  196,  207,  215,  222 

Osage  chert,  value  of  for  road  material 306 

Osage  formation,  description  of 92-96 

Ozarks,  extent  of  in  Illinois 19 

Pachylocrinus  cachensis  n.  sp 170,  173,  (343),  VIII 

P.  spinuliferus  (Worthen 170,  173 

Paint  Creek  fauna,  geologic  range  of 173 

Paint  Creek  formation,  description  of 164-175 


INDEX  411 

PAGE 

Paleontology 85-87,  89,  94-95,  99, 104-106,  115-120, 136-142, 147-150,  164, 170-171, 177- 

178,  182-186,  190,  195-197,  201,  207-209,  211-212,  214-215,  217,  221-222,  227-228,  313-401 

Paleozoic,  definition  of 27 

Palestine  sandstone,  description  of 209-212 

Paragenesis  of  minerals 257-274 

Parallelodon  sp 185 

Pell  fault,  description  of 74 

Pell  mine,  description  of 200 

Pennsylvanian  System,  definition  and  nomenclature  of 91 

description  of 223-229 

Pentremites 116,  150,  151,  152,  153,  156,  172,  208 

P.  arctibrachiatus  Ulrich 148,  IV 

P.  brevis  Ulrich 195,  (369-370),  IV 

P.  buttsi  Ulrich 148,  152,  157,  (323),  IV 

P.  canalis  Ulrich  ? 195 

P.  cervinus 149 

P.  cherokeeus  Hall,  description  and  location  of (371  -372),  X 

P.  conoideus  Hall 99,  100 

P.-  florealis  (part)  Ulrich 314,  816,  817 

P.  fohsi  Ulrich 207,  208,  209,  (370-371),  X 

P.  gemmiformis  Hambach (326),  X 

P.  godoni  DeFrance 148,  149,  152,  157,  170,  173,  (3  1 9),  IV 

P.  lyoni  Ulrich 183 

P.  nodosus  Hambach (356),  IV 

P.  obesus  Lyon 183,  184,  186,  187,  208,  (355),  X 

P.  okawensis  n.  sp 195,  (357),  X 

P.  pinguis  Ulrich .137,  140,  148,  152,  157,  (317),  IV 

P.  planus  Ulrich 152,  186,  319 

P.  platybasis  n.  sp 182,  183,  186,  (355),  IV 

P.  princetonensis  Ulrich 117,  118,  137,  139,  140,  148,  152,  157,  (314),  IV 

P.  pulchellus  Ulrich 137,  140,  (316),  IV 

P.  pyramidatus  Ulrich 170,  173,  194,  (325),  IV 

P.  pyriformis 149 

P.  sp 117,  183,  185,  196,  215 

P.  spicatus  Ulrich 193,  196,  197,  (368),  X 

P.  symmetricus  Hall (324),  IV 

P.  tuscumbiae  Ulrich 137,  140 

Period,  definition  of 27 

Peters  Creek,  relation  of  to  faults 64 

Peters  Creek  faults,  description  of 69-70 

Phanerotrema  ?  sp 95 

Phillipsia  sp 119,  138,  148,  171,  182,  183,  185,  196,  208 

Pholidostrophia 89 

Phractopora  sp 138,  148,  157 

Pierce  mines,  description  of 302 

superficial  deposits  at 256-257 

Pinna 123,  124 

P.        missouriensis 875 

Plant  remains,  in  Casey ville  formation 227 

Degonia  sandstone 217 

Hardinsburg  sandstone 190 

Palestine  sandstone 212 

Tar  Springs  sandstone 201 

Platyceras  sp 196 

Platycrinus 99,  114 

P.  huntsvillae 115,  883 

P.  penicillus  Meek  and  Worthen . 

110,  115,  116,  117,  118,  120, 130, 139,  141, 142,  156,  (333),  V 

Pleurotomaria  ?  sp 138,  215 

Polypora  approximata  Ulrich 215 

P.  cestriensis  Ulrich 138,  140,  148,  157,  183,  196 

P.  corticosa  Ulrich 207 

P.  simulatrix  Ulrich 99 

P.  sp 100,  183,  185,  196,  207,  215 

P.  spinulifera  Ulrich - 138,  140.  182 


412  INDEX 

PAGE 

Polypora  tuberculata  Prout 170,  173,  183,  207 

Population 20 

Posidonomya  ?  sp 95 

Pottsville  group 225-229 

Pre-Devonian  strata,  description  of 79-81 

Preen  mine,  description  of 298 

Prismopora 194 

P.  serrulata  Ulrich 193,  195,  196-197,  198,  (373-374),  XI 

Productus 138.  214 

P.  arkansanus  Girty  ? 214 

P.  burlingtonensis  Hall  ? 95 

P.  cf .  inflatus  McChesney 138,  196 

P.  inflatus  McChesney 138,  148, 157, 183 

P.  inflatus  McChesney  ? 195 

P.  ovatus  Hall 116,  117,  118, 138, 141, 182, 183, 185,  196,  207,  215,  222 

P.  parvus  Meek  and  Worthen 116, 117,  118 

P.  setigera  Hall 95 

P.  sp 138,  215,  222 

Prospecting  for  fluorspar 290,  292-293 

Proterozoic,  definition  of 27 

Pterotocrinus 172, 174,  186,  208 

P.  actus  var.  bifurcatus 372 

P.  bifurcatus  Wetherby 197,  208.  (372),  X 

P.  capitalis  (Lyon) 182,  183,  184,  185,  186,  187,  208,  (360)  VIII 

P.  menardensis  n.  sp 207,  208,  (373),  XI 

P.  platybasis 184 

P.  serratus  n.  sp 170,  173,  (342),  V 

P.  spatulatus 208 

P.  sp 185, 195, 196,  214,  215,  V 

Ptychomphalus  sp 185 

Pugnoides  ottumwa  (White) 116,  117,  118,  139,  142,  156,  (35  1  -352),  VIII 

Pugnoides  ottumwa  (White)  ? 116 

Pustula  punctata  (Martin)  ? 196 

P.  sp 117, 118,  148,  183,  196 

Pyrite,  occurrence  of 254 

"Quartzite  reefs",  association  of  with  faulting 58 

Railroad,  recent  construction  of 19 

Rainey  mine 302 

Randolph  County,  early  subdivisions  of  the  Chester  in 127 

Reelfoot  Lake,  relation  of  to  Hardin  County  faulting , 55 

Reevesville,  Herrin  fault  near 66 

Reforestation,  desirability  of 43 

Relief,    mount  of 21,  39-40 

Renault  funa,  geologic  range  of 157-158 

Renault  formation,  description  of 142-159 

Replacement  of  minerals 259-260 

Residual  deposits 231-232 

Reteporina  flexuosa  (Ulrich) 182,  196 

Reticularia  setigera  (Hall) 

117,  118,  138,  139,  141,  148,  158,  164,  171,  173,  182,  183,  195,  196,  207,  214,  215 

Reverse  fault,  definition  of 30,  31 

Rhipidomella  dubia  (Hall) 99,  117,  118,  (351),  VIII 

Rhombopora  (several  species) 215 

R.  sp 117,  118,  138,  170,  173,  196,  207 

Rhynchonella  explanata  McChesney 360 

R.  ottumwa  White 351 

Rhynchonelloid 184 

Rhynchopora  perryensis  Weller 182,  183,  184,  186 

R.  sp 196 

R.  ?  sp 95 

Ripple  marks,  significance  of 24 


INDEX  413 

PAGE 

Roads,  character  of 42-43 

relation  of  to  topography 42-43 

material  for 306-307 

Rock  Creek,  relation  of  to  faults 64 

Rock  Creek  fault,  description  of 68 

Rock  Creek  Township,  topographic  age  of  hills  in 48-49 

Rose  mine,  description  of 303-304 

Rose  prospect,  Devonian  limestone  at 84 

Rosiclare,  Kinkaid  fossils  collected  near 222 

section  at 113 

topographic  age  of  hills  near 51 

Rosiclare  dikes,  description  of 239 

Rosiclare  fault,  description  of 70 

relation  of  to  fluorspar  deposits 70 

Rosiclare  vein,  description  of 250 

inclination  of 64 

Rosiclare  Mill,  description  of 285-287 

Rosiclare  mine,  description  of 293-295 

Rosiclare  sandstone  member,  lithologic  character  of Ill 

thickness  of 114 

Rosiclare  Township,  limestone  sinks  in 41 

topographic  age  of  hills  in 50,  51 

St.  Louis  chert  as  road  material 306 

St.  Louis  limestone,  description  of 100-106 

Ste.  Genevieve  chert  as  road  material 306 

Ste.  Genevieve  limestone,  controversy  about 129-130 

description  of 106-120 

Sandstones,  origin  of 24 

Schizodus  depressus  Worthen 185 

S.  sp 185 

S.  (?)  sp 185 

Schuchertella  arctistriata  (Hall) 86 

Section  of  Bethel  sandstone 162-163 

Glen  Dean  limestone 195 

Kinkaid  limestone 221 

Menard  limestone 205-206 

Paint  Creek  formation 166,  168 

Ste.  Genevieve  limestone 112-113 

Upper  Warsaw  formation 98 

Vienna  limestone 205-206 

Waltersburg  sandstone 205-206 

Sedimentar}-  rocks,  age  o 79 

formation  of 23-26 

Septopora  cestriensis  Ulrich 183,  207,  215 

S.  n.  sp 117,  118 

S.  similis  n.  sp (348),  VII 

S.  subquadrans  Ulrich 138,  140,  148,  157,  170,  173,  182,  183,  195,  196 

Shales,  origin  of 24,  25 

Shetlerville  fault,  description  of 74 

Shetlerville  fauna,  geologic  range  of 140-141 

Shetlerville  formation,  description  of 133-142 

Siebenthal,  C.  E.,  work  of 277-278 

Sigillaria 125 

Sills,  definition  of 29 

Silver,  occurrence  of 253,  275 

Sink  holes,  drainage  by 21-22,  40-42 

Slickensides,  definition  of 59 

Smith,  W.  S.  Tangier,  work  of 275 

Smithsonite,  occurrence  of  in  bedding  deposits 255 

relation  of  to  mineralization 259 

Soils 20,  44-46 

Solenomya  ?  sp 95 

Soward  intrusion,  description  of 241-242 


414  INDEX 

PAGE 

Sparks  Hill,  Clore  fossils  collected  near 214 

Sparks  Hill  intrusion,  description  of 242-244 

Mississippian  pebbles  in 81 

Spathiocaris  emersoni 89 

Sphalerite,  deposition  of 258 

description  of 253 

separation  of 293 

Sphenopteris  communis  Lesquereux 227 

S.  sp.  undet 201 

Sphenotus  sp 117,  118,  185 

S.  ?sp 95 

Spirifer 123,  124 

S.  audaculus  (Conrad)  ? • 86 

S.  bifurcatus  Hall 99,  119,  120 

S.  breckenridgensis  Weller 138,  141 

S.  concinnus 86 

S.  divaricatus  Hall 86 

S.  duodenarius  Hall 86 

S.  gregarius  Clapp  ? 86 

S.  increbescens  Hall 120,  149,  206,  207,  208,  209,  214,  215,  (374-375),  XI 

S.  increbescens  Hall,  var 138,  183,  195,  196 

S.  increbescens  var 141,  185 

S.  increbescens  var.  americana  Swallow 185 

S.  increbescens  var.  transversalis  Hall 148,  158,  171,  173 

S.  iowensis  Owen? 86 

S.  lateralis  Hall 99,  100 

S.  leidyi  Norwood  and  Pratten 

117, 118,  120,  138,  141,  148, 149,  158,  182,  183,  195,  196,  222 

S.  pellaensis  Weller 116,  117,  118,  119,  120 

S.  segmentum  Hall 85 

S.  subequalis  Hall : 99,  100 

S.  tenuicostatus  Hall 99 

S.  varicosum  Hall 86 

S.  cf .  worthenanus  Schuchert 86 

Spiriferina  sp 117,  118 

S.  spinosa  (Norwood  and  Pratten) 

.  148,  158,  171,  172,  173,  174,  182,  183,  185,  195,  196,  207,  215,  (353-354),  VIII 

S.  subspinosa  n.  sp 138,  139,  142,  (352),  VIII 

S.  subtexta  White  ? 99 

S.  transversa  (McChesney) 116,  117,  118, 

138, 139,  141,  148,  158,  172,  174,  182,  183,  195,  196,  207,  214,  215,  (353),  VIII 

Spirorbis  sp 137,  183 

Steel  industry,  importance  of  fluorspar  deposits  to 287 

Stenopora  cestriensis  Ulrich 137,  140,  183,  207 

S.  cestriensis  Ulrich  ? 215 

S.  montifera  Ulrich 137,  140 

S.  montifera  Ulrich  ? 117,  118 

S.  sp 137,  148,  207,  215 

S.  tuberculata  (Prout) 117,  118,  137,  139,  140,  149,  157,  171,  173,  183,  185,  196 

Stewart  mine,  description  of 300 

relation  of  to  Wolrab  Mill  fault 67 

Stibnite,  occurrence  of 254 

Stigmaria 125 

Stock  raising,  desirability  of 45-46 

Stone  Hill,  fossil  collections  from 227 

maximum  faulting  near 73 

Stone  for  roads 306-307 

Straparollus  sp 117,  119 

Strata,  definition  of 25 

Stratigraphic  geology 77-145 

Streams 21,  33-34,  39,  40 

Streblotrypa  distincta  Ulrich 207 

S.  nicklesi  Ulrich 138,  140,  148,  157,  170,  173,  183,  215 

S.  p 196,215 

Strike,  definition  of 32 


INDEX  415 

PAGE 

Stroboceras  sp 185 

Structure 29-32,  56,  64 

Structural  geologj^ 55-75 

Sulcatopinna  missouriensis  (Swallow) 208,  209,  222,  (375-376),  XI 

Superficial  fluorspar  deposits,  methods  in  mining  of 282 

description  of 256-^57 

Surficial  deposits 231-234 

Systems,  definition  of 27 

Talarocrinus 149,  150,  153,  154,  155,  156,  158,  162,  172,  (336) 

T.  buttsi  Ulrich 137,  140, 142,  149 

T.  cornigerus  (Shumard) (340),  VI 

T.  inflatus  Ulrich (337),  VI 

T.  ovatus  Worthen (340),  VI 

T.  planus  n.  sp (342),  VI 

T.  trijugis  Miller  and  Gurley 137,  140,  148,  149,  157,  (338),  IV 

Talus  deposits,  definition  of 35 

Tar  Springs  sandstone,  description  of 198,  202 

Taxocrinus  sp 170,  173 

Tentaculites  bellulus  Hall 86 

Terebratula  trinuclea  Hall 854 

Thamniscus  furcillatus  Ulrich 118,  138,  140,  170,  173,  183 

T.  ramulosus  Ulrich 138,  140 

Threemile  Creek  fault,  description  of 73 

Thrust  fault,  definition  of 30,  31 

Topography 20,  39-40 

development  of 32-36 

history  of 47-52 

relation  of  to  farming 43-44 

geologic  structure 64 

roads 42-43 

Tower  Rock,  St.  Louis  limestone  at 102 

Towns 20 

Tradewater  formation,  coal  in 228 

description  of 228-229 

Triplophyllum 99 

T.  sp 117,118 

T.  spinulosum  (Milne-Edwards  and  Haime) 

137, 139,  140,  148,  157,  170,  173,  182,  183,  185,  195,  196,  207,  215,  222 

Twitchell  mine,  description  of 298 

Ulrich,  E.  0.,  opinions  of  concerning  Renault  formation 150-159 

work  of 126-132,  275 

Unconformities,  definition  of 26-27 

Upper  Mississippian  series,  se    Chester  group. 

Vein  deposits,  description  of 248-254 

methods  used  in  mining  of 282 

minerals  in 252-254 

shapes  of 251-252 

Vienna  limestone,  description  of 202 

section  of 205-206 

Volcanic  breccia,  description  of 237 

Wallace  Branch  fault,  description  of 74 

Waltersburg  sandstone,  description  of 202 

section  of 205-206 

Warsaw  chert,  value  of  for  road  material 306 

Warsaw  formation,  description  of 97-100 

Weathering,  definition  of 34 

Weller,  J.  Marvin,  work  of 218 

Whittleseya  microphylla  Lesquereux 227 

Williams  Hill,  altitude  of 19 


416  INDEX 

PAGE 

Wind-blown  deposits 223-234 

Wolrab  Mill,  outcrop  of  Warsaw  formation  near 99 

Wolrab  Mill  fault,  description  of 67 

Zaphrentis  spinulif era 149 

Zeacrinus  maniformis 149 

Z.  sp 195 

Zygopleura  sp 117,  119 


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